Mohyee Mikhemar

An 800-MHz–6-GHz Software-Defined Wireless Receiver in 90-nm CMOS

A software-defined radio receiver is designed from a low-power ADC perspective, exploiting programmability of windowed integration sampler and clock-programmable discrete-time analog filters. To cover the major frequency bands in use today, a wideband RF front-end, including the low-noise amplifier (LNA) and a wide tuning-range synthesizer, spanning over 800 MHz to 6 GHz is designed. The wideband LNA provides 18-20 dB of maximum gain and 3-3.5 dB of noise figure over 800 MHz to 6 GHz. A low 1/f noise and high-linearity mixer is designed which utilizes the passive mixer core properties and provides around +70 dBm IIP2 over the bandwidth of operation. The entire receiver circuits are implemented in 90-nm CMOS technology. Programmability of the receiver is tested for GSM and 802.11g standards

An 800MHz to 5GHz Software-Defined Radio Receiver in 90nm CMOS

A 90nm CMOS RX operates over the 800MHz to 5GHz band uses a passive FET mixer driven by a capacitively coupled RF transconductor, and a combination of CT and DT analog FIR and MR filters to achieve >100dB of programmable anti-aliasing. The RX chain has 5 to 5.5dB NF, -3.5dBm IIP3, 39dBm IIP2, 10 to 66dB of gain, and draws 11.4mA from 2.5V and 8 to 28mA (depending on RX mode) from 1V

Software-defined radio receiver: dream to reality

This article describes a fully integrated 90 nm CMOS software-defined radio receiver operating in the 800 MHz to 5 GHz band. Unlike the classical SDR paradigm, which digitizes the whole spectrum uniformly, this receiver acts as a signal conditioner for the analog-to-digital converters, emphasizing only the wanted channel. Thus, the ADCs operate with modest resolution and sample rate, consuming low power. This approach makes portable SDR a reality

An Outphasing Power Amplifier for a Software-Defined Radio Transmitter

A software-defined radio (SDR) transmitter needs a universal modulator and power amplifier to support any modulation in any band. There is a simple solution, namely, a Cartesian I-Q upconverter followed by a linear power amplifier, but for complex modulations its power conversion efficiency is often under 10%. Therefore, the search continues for a more efficient solution. One possibility is to harness the high efficiency of a saturated power amplifier but somehow make it deliver amplitude-modulated waveforms. Polar modulation has found use in enabling EDGE on GSM handsets, but we believe outphasing, or linear amplification using nonlinear components (LINC), offers a more enduring solution for a broader class of modulations.

A Multiband RF Antenna Duplexer on CMOS: Design and Performance

An RF duplexer has been fabricated on a CMOS IC for use in 3G/4G cellular transceivers. The passive circuit sustains large voltage swings in the transmit path, and isolates the receive path from the transmitter by more than 45 dB across a bandwidth of 200 MHz in 3G/4G bands I, II, III, IV, and IX. A low noise amplifier embedded into the duplexer demonstrates a cascade noise figure of 5 dB with more than 27 dB of gain. The duplexer inserts 2.5 dB of loss between power amplifier and antenna.

An on-chip wideband and low-loss duplexer for 3G/4G CMOS radios

A wideband integrated RF duplexer supports 3G/4G bands I, II, III, IV, and IX, and achieves a TX-to-RX isolation of more than 55dB in the transmit-band, and greater than 45dB in the corresponding receive-band across 200MHz of bandwidth. A 65nm CMOS duplexer/LNA achieves a transmit insertion loss of 2.5dB, and a cascaded receiver noise figure of 5dB with more than 27dB of gain, exceeding the commercial external duplexers performance at considerably lower cost and area.

Digital Compensation of Cross-Modulation Distortion in Software-Defined Radios

The wideband RF receiver in a software-defined radio (SDR) system suffers from the nonlinear effects caused by the front-end analog processing. In the presence of strong blocker (interference) signals, such nonlinearities introduce severe cross modulation over the desired signals. This paper investigates how the cross-modulation distortion can be compensated for by using digital signal processing techniques. In the proposed solution, the SDR scans the wide spectrum and locates the desired signal and strong blocker signals. After down-converting these signals separately to the baseband, the baseband processor processes them jointly to mitigate the cross-modulation interferences. As a result, the sensitivity of the wideband RF receiver to the nonlinearity impairment can be significantly lowered, simplifying the RF and analog circuitry design in terms of implementation cost and power consumption. The proposed approach also demonstrates how mixed-signal, i.e., joint analog and digital, processing techniques play a critical role in the emerging SDR and cognitive radio technologies.

Digital compensation of RF nonlinearities in software-defined radios

The wideband RF receiver in a software-defined radio (SDR) system suffers from the nonlinear effects caused by the front-end analog processing. In the presence of strong blocker (interference) signals, nonlinearities introduce severe cross modulation over the desired signals. This paper investigates how the nonlinear distortions can be compensated for by using digital signal processing techniques. In the proposed solution, the SDR scans the wide spectrum and locates the desired signal and strong blocker signals. After down-converting these signals separately into the baseband, the baseband processor processes them jointly to mitigate the cross-modulation interferences. As a result, the sensitivity of the wideband RF receiver to the non-linearity impairment can be significantly lowered, simplifying the RF and analog circuitry design in terms of implementation cost and power consumption.