Gerhardus J.M. Wienk

A software-defined radio receiver architecture robust to out-of-band interference

In a software-defined radio (SDR) receiver it is desirable to minimize RF band-filtering for flexibility, size and cost reasons, but this leads to increased out-of-band interference (OBI). Besides harmonic and intermodulation distortion (HD/IMD), OBI can also lead to blocking and harmonic mixing. A wideband LNA [1, 2] amplifies signal and interference with equal gain. Even a low gain of 6dB can clip 0dBm OBI to a 1.2V supply, blocking the receiver. Hard-switching mixers not only translate the wanted signal to baseband but also the interference around LO harmonics. Harmonic rejection (HR) mixers have been used [3, 1, 4], but are sensitive to phase and gain mismatch. Indeed the HR in [4] shows a large spread, whereas other work only shows results from one chip [3, 1]. This paper describes techniques to relax blocking and HD/IMD, and make HR robust to mismatch.

A 90μW 12MHz Relaxation Oscillator with a -162dB FOM

Both ring oscillators and relaxation oscillators are subsets of RC oscillators featuring large tuning ranges and small areas. Such relaxation oscillators have two advantages with respect to ring oscillators: 1) they have a constant frequency tuning gain; and 2) their phase can be read out continuously due to their triangular (or sawtooth) waveform. A major disadvantage of practical relaxation oscillators is their poor phase-noise compared to ring oscillators.

Achieving Wideband sub-1dB Noise Figure and High Gain with MOSFETs if Input Power Matching is not Required

A 0.18 mum CMOS low noise amplifier (LNA) achieves sub-1 dB noise figure over more than an octave of bandwidth without external noise matching components. It is designed for a future radio telescope, requiring millions of cheap LNAs mounted directly on phased array antenna elements. The short distance between antenna and LNA and low frequency below 2 GHz allows for using an LNA with reflective input impedance, increasing the gain with 6 dB. Without any matching network, very low noise figure is achieved over a wide bandwidth. At 90 mW power, sub-1 dB Noise is achieved for 50 Omega source impedance over a 0.8-1.8 GHz band without external coils, and S21>20 dB, OIP2>25 dBm and OIP3>15 dBm. Preliminary results with 150 Omega source impedance show noise temperatures as low as 25 K around 900 MHz.

A multipath technique for canceling harmonics and sidebands in a wideband power upconverter

Switching mixers are power-efficient but produce unwanted harmonics and sidebands. A multipath technique to clean up the spectrum using digital circuits and mixers, but no filters, is applied to a 0.13mum CMOS power upconverter. The circuit delivers 8mW from dc to 2.4GHz with 11% drain efficiency, with spurs <-40dBc over more than 4 octaves in frequency, and consumes 228mW from a 1.2V supply

A wideband IM3 cancellation technique for CMOS attenuators

In the receiver path and in spectrum analyzers, typically gain control blocks are used to limit the incident power to the level that the receiver circuitry can handle without degrading the linearity; in the transmitter path stringent power control is also desirable. Although variable-gain amplifiers (VGAs) traditionally implement the gain-control block, attenuators based on FET transistors show superior performances on linearity, power handling capability and power consumption.

A CMOS spectrum analyzer frontend for cognitive radio achieving +25dBm IIP3 and −169 dBm/Hz DANL

A dual RF-receiver preceded by discrete-step attenuators is implemented in 65nm CMOS and operates from 0.3-1.0 GHz. The noise of the receivers is reduced by cross-correlating the two receiver outputs in the digital baseband, allowing attenuation of the RF input signal to increase linearity. With this technique a displayed average noise level below -169 dBm/Hz is obtained with +25 dBm IIP3, giving a spurious-free dynamic range of 89 dB in 1 MHz resolution bandwidth.

Optical Power Efficiency Versus Breakdown Voltage of Avalanche-Mode Silicon LEDs in CMOS

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A Software-Defined Radio Receiver in 65nm CMOS Robust to Out-of-Band Interference

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A 12MHz Switched-Capacitor Relaxation Oscillator with a Nearly Minimal FoM of -161dBc/Hz

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A Wideband Flexible Power Upconverter for Software Defined Radios

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