A 900-MHz RF front-end with integrated discrete-time filtering

Abstract

Abstruct-Discrete-time analog filters, rather than off-chip components, have been used to perform frequency selection and down conversion in the integrated front-end for a 900-MHz RF receiver. The first stage of frequency down conversion is implemented with a subsampling switched-capacitor sample-andhold circuit clocked at 78 MHz. Subsequent stages of discrete-time filtering are realized using switched-capacitor biquadratic filters. An experimental prototype of the front-end had been integrated in a 0.6-pm BiCMOS technology. The circuit provides a system gain of 36 dB and 32 dB suppression of interfering channels over a 40 MHz bandwidth. Referred to the system input, the thirdorder intercept-point is -16 dBm, and the spot input-referred noise is -82 dBm over a 30 kHz bandwidth. The experimental circuit dissipates 90 mW from a 3.3-V supply and occupies an active area of 1.9 x 1.9 mm'.

Wireless Receiver Architectures Towards 5G: Where Are We?

“…In research, a trend to use switching circuits instead of a mixer and/or using the switching to obtain a comb-filterlike functionality can be observed [41]- [48], sometimes completely omitting an LNA. Again, these topologies aim at higher integration and flexibility in operating frequency, targeting to replace the SAW/BAW/FBAR filters currently used.…”

“…An alternative approach to obtain flexibility for 5G is to use switching circuits instead of a mixer and/or using the switching to obtain a comb-filter-like functionality [41]- [48]. However, obtaining resilience to out-of-band blockers combined with a good noise figure and intermodulation performance over a wide frequency range remains challenging [48].…”

Challenges in integrated CMOS transceivers for short distance wireless

“…In this approach, the lowest power solution would involve a tradeoff analysis between the input rate of the A/D converter and the complexity of anti-aliasing downsampling filters in multi-stage configuration. The use of multi-stage filtering allows reuse of anti-aliasing filters [24] by appropriate selection of × in relation with . In this approach, channel select filtering, demodulation and baseband processing are done in the digital domain following the A/D converter.…”

“…A general scheme based on sub-sampling operation is presented in [24] and shown in Fig. 11 in which the RF input is sampledand-held and followed directly by discrete time analog signal pro- cessing.…”

“…Another approach to direct-conversion receiver is sub-sampling [24,25]. The basic approach is to sample the RF signal at an integer fraction of carrier frequency which is greater than twice the bandwidth of the modulating signal.…”