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Operazionnie ysiliteli ,ZAP/AZP & (ïðîäîëæåíèå)
milstar: 1941: First (vacuum tube) op-amp An op-amp, defined as a general-purpose, DC-coupled, high gain, inverting feedback amplifier, is first found in US Patent 2,401,779 "Summing Amplifier" filed by Karl D. Swartzel Jr. of Bell labs in 1941. This design used three vacuum tubes to achieve a gain of 90dB and operated on voltage rails of ±350V. ###################################################### It had a single inverting input rather than differential inverting and non-inverting inputs, as are common in today's op-amps. Throughout World War II, Swartzel's design proved its value by being liberally used in the M9 artillery director designed at Bell Labs. ######################################################################### This artillery director worked with the SCR584 radar system to achieve extraordinary hit rates (near 90%) that ####################################################################### would not have been possible otherwise.[3] ########################### http://en.wikipedia.org/wiki/Operational_amplifier
milstar: Characterization of IQ Modulators Counts On Flexible Signal Generator StimulusApplication NoteThe Role of IQ Modulators in MobileTelecommunicationModern mobile telecommunication relies on quadratureamplitude modulation (QAM) to mix digital transmissiondata onto an RF carrier. In QAM, every logical state isassigned to a specific amplitude and phase value. Anexample for QAM is Quadrature Phase-Shift-Keying(QPSK) which encodes four possible symbol bit-pairsinto phase shifts of a sine wave of ±45º and ±135º asshown in Figure 1. Higher order QAM makes it possibleto transmit more bits per symbol. The most commonforms are 16-QAM, 64-QAM, 128-QAM and 256-QAM.An efficient way to generate the modulating (baseband)signal with a specific amplitude and phase is toseparate the signal vector into an in-phase "I"component with phase 0º and a quadrature "Q"component with phase 90º. This reduces the task tomodulating the amplitudes of two sine wave signals. To illustrate, Table 2 lists the I and Q amplitudescorresponding to the four logical states for the QPSKexample discussed here In a next step, the baseband signal is then modulated orup-converted onto the RF carrier with an IQ modulator.These modulators are available as integrated circuitsfrom a number of semiconductor manufacturers. Inprincipal, they consist of two multipliers that are eachdriven by the carrier or local oscillator (LO) frequency,one of them shifted by 90º against the other. Theoutputs of these multipliers are combined to themodulated RF vector signal. https://www.newark.com/pdfs/techarticles/tektronix/Characterization_of_IQ_modulators.pdf
milstar: https://www.analog.com/media/en/technical-documentation/data-sheets/55881fb.pdf The LTC®5588-1 is a direct conversion I/Q modulator designed for high performance wireless applications. It allows direct modulation of an RF signal using differential baseband I and Q signals. It supports LTE, GSM, EDGE, TD-SCDMA, CDMA, CDMA2000, W-CDMA, WiMax and other communication standards. It can also be config-ured as an image reject upconverting mixer, by applying 90° phase-shifted signals to the I and Q inputs. The I/Q baseband inputs drive double-balanced mixers. An on-chip balun converts the differential mixer signals to a 50Ω single-ended RF output. F
milstar: https://www.analog.com/media/en/technical-documentation/data-sheets/AD6620.pdf he AD6620 is a digital receiver with four cascaded signal-processing elements: a frequency translator, two fixed-coefficient decimating filters, and a programmable coefficientdecimating filter. All inputs are 3.3 V LVCMOS compatible.All outputs are LVCMOS and 5 V TTL compatible.As ADCs achieve higher sampling rates and dynamic range, itbecomes increasingly attractive to accomplish the final IF stageof a receiver in the digital domain. Digital IF Processing is lessexpensive, easier to manufacture, more accurate, and moreflexible than a comparable highly selective analog stage
milstar: Programmable full-scale input range allows trade-off between SNR and SFDR enabling the design of more sensitive radar systems with the ability to acquire and track smaller targets with better accuracy. See chart below. https://www.radiolocman.com/news/new.html?di=67247 2.5 v SNR 76dbf SFDR 100 dbf 100 mhz 160msps
milstar: Broadened SFDR Definition for Wideband Digital Receivers IMD2 crashing the party requires a refreshed definition of the popular receiver FOM instantaneous spurious-free dynamic range (SFDR). SFDR specifies how far down a receiver can detect a small signal when there are multiple larger signals creating IMD spurs. SFDR is specified in dB relative to the large signals. Traditionally, SFDR is defined in terms of IMD3 products, along with NF and processing bandwidth. IMD3-referenced SFDR is derived in many texts, and is sometimes clarified as instantaneous SFDR, which is what we mean in this article.5,6 We’ll call it SFDR3: https://www.analog.com/en/analog-dialogue/articles/sfdr-considerations-in-multi-octave-wideband-digital-receivers.html
milstar: Spectral resolution and sensitivity improve as the FFT bin narrows, which requires increasing N. Longer pulse widths and PRIs require finer resolution to resolve closer spectral lines, which means larger N for proper detection. Increasing N improves spectral line resolution, but only within the IF bandwidth defined by M. If too high a decimation is used, increasing N improves the spectral resolution within the IF BW set by M, but cannot recover the missing signal bandwidth. For example, a pulse train with a pulse width below the minimum receiver pulse width will have a frequency domain sinc function whose main lobe exceeds the decimation bandwidth. Increasing N will help resolve the PRF of the train, but will do nothing to resolve the pulse width; that information is lost. The only fix is to decrease decimation M, increasing the IF bandwidth. Decimation, FFT, and Detection of Pulse Trains EW wideband digital receivers spend a lot of their effort de-interleaving, identifying, and tracking simultaneous incident radar pulse trains. Carrier frequency, pulse width, and pulse repetition interval (PRI) are radar signatures that are critical in figuring out who’s who. Both the time and frequency domain are used in detection schemes.9 An overarching objective is to sense, process, and react to the pulse trains in as short a time duration as possible. Dynamic range is critical because the EW receiver needs to simultaneously track multiple distant targets while being bombarded with high energy jamming pulses. Pulse Train FFT Examples Two pulse train examples are presented. The first represents a pulsed doppler radar exhibiting a very short PW (100 ns) at 10% duty cycle, resulting in very high PRF. The second simulates a pulsed radar exhibiting comparatively longer PW and PRI (lower duty cycle, lower PRF). The following plots and tables illustrate the impact of decimation M and FFT length N on time, sensitivity (noise floor), and spectral resolution. Table 1 summarizes the parameters for easy comparison. The fictional values do not represent specific radars but are nevertheless in a realistic ballpark.10 https://www.analog.com/en/analog-dialogue/articles/sfdr-considerations-in-multi-octave-wideband-digital-receivers.html
milstar: https://www.analog.com/media/en/technical-documentation/data-sheets/ad9174.pdf Dual, 16-Bit, 12.6 GSPS RF DAC and Direct Digital Synthesizer
milstar: japanese fabless chip company MegaChips Corp., has announced a 16nm FinFET analog ASIC that integrates a gigabit-class analog-to-digital converter (ADC) and digital-to-analog converter (DAC) to create an analog front end (AFE) for 5G networks and other high-speed applications. The analog ASIC provides a 14-bit, 3.4-Gsps/6.8-Gsps ADC and 12-bit, 3.4-Gsps/6.8-Gsps DAC—in a 16nm SoC that saves power, cost and space when compared to a circuit made of an FPGA and discrete ADCs. The Analog Mega Block (AMB) intellectual property design includes ADCs, DACs, PGAs, IAMPs, PLLs and filters. "Achieving compliance with today’s communications standards is a long and complicated process," said Masahiro Konishi, general manager of MegaChips. "We have a dedicated team of experts focused on AMB development. They work alongside our customers as a virtual R&D team, from the initial design specification through certification and production ramp up." "MegaChips has a long track record of successfully delivering state-of-the-art high-speed ASICs for passive optical networks (PON), home networks (HPNA, G.hn), and access networks (G.fast)," commented Yuji Sakuma, general manager of MegaChips. MegaChips previously added a 28nm AMB with 0.6-Gsps/1.2-Gsps, 14-bit ADC and DAC and a 65nm/130nm AMB with 200-Msps/400-Msps 12-bit ADC and DAC to its analog ASIC IP family. https://www.mwee.com/news/16nm-finfet-analog-asic-integrates-adcdac-5g
milstar: For example, assume an input signal of 30 MHz and arequired SNR of 80 dB. This, in turn, requires a clock withjitter of no more than 531 picoseconds. This assumes anADC SNR that is much better than 80 dB, making jitter thelimiting factor.Clocks and oscillators are often specified in terms ofphase noise rather than timing jitter. The two are similar,and phase noise can be converted to jitter. Raltron offers aWeb-based calculator [2] for this purpose.Wide Dynamic Range DigitizingAs mentioned previously, recording weather radar sig-nals requires a minimum of 105 dB of dynamic range. Sincethe dynamic range of available high speed ADCs is limitedto 90 dB (with processing gain), with further reductionsdown to 80 dB due to the clock source (jitter), a simple ADCis not sufficient.Symtx Inc. has implemented a dual ADC scheme toincrease digitizer dynamic range as shown in Figure 3. Thedesign uses a high-gain channel to process low-level sig-nals and a low-gain channel to process high-level signals,with simultaneous sampling of both channels in parallel. http://www.highfrequencyelectronics.com/Sep08/HFE0908_S_Crean.pdf he gain difference between the high-level and low levelADCs is compensated with an appropriate n-bit left shiftto give the correct scaling. A DSP after the two ADCs thenselects the correct ADC output, adjusts for gain, andmerges the two to create a 20-bit word with the desireddynamic range.The process is essentially an instantaneous AGC whichresponds to the signal amplitude at the input. Since rangebins for weather radars are on the order of 1 microsecond,the DSP operates by scanning the data for each range binto determine the maximum signal amplitude. If this iswithin the maximum level for the high-gain (low-signal-level) ADC, it is used for data collection (to maximize signalresolution). If any sample exceeds this threshold, all data inthe range bin is collected using the low-gain (high-signal-level) ADC
milstar: Âñå ðàçðàáîòàííûå ìèêðîñõåìû íå óñòóïàþò ïî õàðàêòåðèñòèêàì ñâîèì àíàëîãàì, à â äàëüíåéøåì ïëàíèðóåòñÿ âûéòè â áîëåå âûñîêî÷àñòîòíóþ îáëàñòü(X äèàïàçîíà), ñ âîçìîæíûì ïðèìåíåíèåì òåõíîëîãèè SiGe 0.13 ÁèÊÌÎÏ. https://mri-progress.ru/publicatsii/%D0%9A%D0%A0%D0%95%D0%9C%D0%9D%D0%98%D0%99-%D0%93%D0%95%D0%A0%D0%9C%D0%90%D0%9D%D0%98%D0%95%D0%92%D0%AB%D0%95%20%20%D0%9A%D0%92%D0%90%D0%94%D0%A0%D0%90%D0%A2%D0%A3%D0%A0%D0%9D%D0%AB%D0%95%20%D0%9C%D0%9E%D0%94%D0%A3%D0%9B%D0%AF%D0%A2%D0%9E%D0%A0%D0%AB%20%D0%98%20%D0%94%D0%95%D0%9C%D0%9E%D0%94%D0%A3%D0%9B%D0%AF%D0%A2%D0%9E%D0%A0%D0%AB.pdf
milstar: http://vita.mil-embedded.com/articles/very-sampling-serial-adcs-embedded-systems/ While the JESD204B standard has simplified multichannel synchronization by using deterministic latency, minimal latency is needed in some applications such as electronic warfare (EW) and radar applications where actions are required immediately after detection. For these applications, the LVDS interface should still be considered, as the JESD204B-compliant data converter’s delay in serializing the data is omitted. However, applications such as radar warning receivers (RWR) or COMINT that are receiver-only applications tolerate the latency brought on by the JESD204B serialization. These applications thus can benefit from the last generations of ADCs driven by the mass market of telecommunication infrastructure, allowing very high-speed sampling and reducing the complexity of the analog part of the system.
milstar: Emerging threats drive RF and microwave component design trends for electronic warfare Story January 14, 2021 https://militaryembedded.com/radar-ew/rf-and-microwave/emerging-threats-drive-rf-and-microwave-component-design-trends-for-electronic-warfare “Frequency-hopping is now more complex, and adversaries are moving as high as 130+ GHz for use in military terrestrial and on-orbit systems,” D’Arcy explains. “Furthermore, there is a need to incorporate more sophisticated digital methods into electronic attack or defense systems, which will require greater speed and efficiency when moving the signal of interest from analog to digital and back.” “This requires advances in gallium nitride (GaN) amplifiers, up- and down-converters, filters, drivers, and exciters.” (Figure 1.) For both high-speed analog-to-digital (ADC) and digital-to-analog (DAC) converters (digitizers), the push is to enable direct sampling by exceeding 20 Gsamples/sec and above with an increasing number of output and input bits,” D’Arcy says. “Of equal importance, due to the ability to defeat systems with measurable processing delay, is the requirement to reduce latency at the converter and the FPGA [field-programmable gate array] that is induced prior to data reaching the digital backbone. Bent pipe or digitally controlled analog still have significant use due to their minimal latency.” To drive this reduction in latency and manage the scale of the greater data, “more processing fabric is being incorporated into the digitizers,” he adds. “This allows for extensive digital decimation and loopback control to be done closer to the antenna for the ADC signal chain. Conversely, fabric to enable digital data expansion and beamforming are being incorporated into the DAC for its related signal chain.” Another design trend emerging is increasing demand from the DoD for trusted RF and microwave solutions, coming as adversaries develop new electronic capabilities. “It’s no longer acceptable to develop a single system that can be fielded for 10 years without regular modernization,” says Ken Hermanny, senior director and general manager of Mercury’s West Caldwell, New Jersey, facility. “We leverage open standards from chip scale to system scale to incorporate the most advanced technologies and make them accessible to our aerospace and defense customers.”
milstar: Yet another trend is dual-purpose solutions. “In the past, we offered banded-solution approaches leveraging our cellular infrastructure devices,” Smith states. “As a key component supplier within the cellular infrastructure market, many of the same devices used for communications also had a dual purpose for electronic warfare. https://militaryembedded.com/radar-ew/rf-and-microwave/emerging-threats-drive-rf-and-microwave-component-design-trends-for-electronic-warfare
milstar: One key similarity between EW and radar requirements is the demand for increased capability within a single transistor. “For radar, the power levels continue to be much higher than requirements for electronic warfare or communications,” Smith notes. “In many cases, the key metric for radar is efficiency – always trying to push the boundaries and achieve as high efficiency as possible. Efficiency also matters within EW, but it’s based on the market bandwidth and integration. While both radar and EW require high-performance solutions in compact SWaP-optimized packaging, Hermanny points out that EW has its own unique challenges: “Unlike radar, where both transmit and receive sides of the system are defined, an electronic warfare system must operate on previously unknown signals,” he explains. For example, an EW system might need to receive an adversary’s radar signal, process it, and retransmit that signal. “Since the electronic warfare system designer can’t predict the frequency of that radar signal, they need to design the electronic warfare system to operate over a very wide range of frequencies,” Hermanny says. “This unknown element requires electronic warfare systems to be dynamically configurable and operate over a very wide frequency range.” https://militaryembedded.com/radar-ew/rf-and-microwave/emerging-threats-drive-rf-and-microwave-component-design-trends-for-electronic-warfare
milstar: Early in the receiver design the A/D operation is chosen. Sampling in the 2nd Nyquist zone has become popular. The primary benefits are that the 2nd IF harmonics produced either in the mixer or in amplifier non-linearities are out of band and can be filtered. Sampling in a higher Nyquist zone produces a digital downconversion and can be quite useful when frequency planning. The primary compromise of IF sampling is the A/D performance degrades as the input frequency increases. This concern must be balanced with other tradeoffs in the overall receiver design. https://www.mwrf.com/technologies/components/article/21845907/receiver-design-considerations-in-digital-beamforming-phased-arrays Peter Delos is lead RF/RFIC engineer for Lockheed Martin Corp. ############################ 16-Bit, 200 MSPS/250 MSPS Analog-to-Digital ConverterData Sheet AD9467 https://www.analog.com/media/en/technical-documentation/data-sheets/AD9467.pdf SFDR at 170 MHz at 250 MSPS 92 dBFS at −1 dBFS 100 dBFS at −2 dBFS = 98 dbc -------------------------------------------------
milstar: Spur Generation +-n Fin +-kFs
milstar: https://neuron.eng.wayne.edu/auth/ece4330/practical_sampling.pdf
milstar: Take a quick numerical example. The AD974 is a 200ksps ADC and let's assume that the highest frequency you want to capture is 75kHz. Ok so we design a low pass filter with 75kHz cut off frequency. With 200kHz sampling frequency, Nyquist is 100kHZ, and the first image is at 150kHz. To maintain accuracy you need a filter which will attenuate any signals at 150kHZ to better than 74dB (in order to maintain a 12bit dynamic range). So filter must roll off approx 70dB in one octave, that's a 23 pole filter you need So you can see that even to sample at frequencies close to Nyquist you need a fairly expensive filter. https://ez.analog.com/data_converters/high-speed_dacs/w/documents/2786/ad974-antialiasing-filter
milstar: Frequency Folding Tool https://www.analog.com/en/design-center/interactive-design-tools/frequency-folding-tool.html
milstar: https://www.analog.com/media/en/training-seminars/design-handbooks/MixedSignal_Sect2.pdf
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