In this paper, we propose a discrete-time IIR low-pass filter that achieves a high-order of filtering through a charge-sharing rotation. Its sampling rate is then multiplied through pipelining. The first stage of the filter can operate in either a voltage-sampling or charge-sampling mode. It uses switches, capacitors and a simple gm-cell, rather than opamps, thus being compatible with digital nanoscale technology. In the voltage-sampling mode, the gm-cell is bypassed so the filter is fully passive. A 7th-order filter prototype operating at 800 MS/s sampling rate is implemented in TSMC 65 nm CMOS. Bandwidth of this filter is programmable between 400 kHz to 30 MHz with 100 dB maximum stop-band rejection. Its IIP3 is +21 dBm and the averaged spot noise is 4.57 nV/ Hz. It consumes 2 mW at 1.2 V and occupies 0.42 mm 2 .
We present an ultra-low-power Bluetooth lowenergy (BLE) transceiver (TRX) for the Internet of Things (IoT) optimized for digital 28-nm CMOS. A transmitter (TX) employs an all-digital phase-locked loop (ADPLL) with a switched current-source digitally controlled oscillator (DCO) featuring low frequency pushing, and class-E/F 2 digital power amplifier (PA), featuring high efficiency. Low 1/ f DCO noise allows the ADPLL to shut down after acquiring lock. The receiver operates in discrete time at high sampling rate (∼10 Gsamples/s) with intermediate frequency placed beyond 1/ f noise corner of MOS devices. New multistage multirate charge-sharing bandpass filters are adapted to achieve high out-of-band linearity, low noise, and low power consumption. An integrated on-chip matching network serves to both PA and low-noise transconductance amplifier, thus allowing a 1-pin direct antenna connection with no external band-selection filters. The TRX consumes 2.75 mW on the RX side and 3.7 mW on the TX side when delivering 0 dBm in BLE. Index Terms-All-digital PLL (ADPLL), Bluetooth low energy (BLE), digitally controlled oscillator (DCO), discrete-time (DT) receiver (RX), Gaussian frequency shift keying (GFSK), intermediate frequency (IF), Internet of Things (IoT), low-power (LP) transceiver (TRX), matching network, transmit/receive (T/R) switch, transmitter (TX).
A complex quadrature charge-sharing (CS) technique is proposed to implement a discrete-time band-pass filter (BPF) with a programmable bandwidth of 20-100 MHz. The BPF is part of a cellular superheterodyne receiver and completely determines the receiver frequency selectivity. It operates at the full sampling rate of up to 5.2 GHz corresponding to the 1.2 GHz RF input frequency, thus making it free from any aliasing or replicas in its transfer function. Furthermore, the advantage of CS-BPF over other band-pass filters such as N-path, active-RC, -, and biquad is described. A mathematical noise analysis of the CS-BPF and the comparison of simulations and calculations are presented. The entire 65 nm CMOS receiver, which does not include a front-end LNTA for test reasons, achieves a total gain of 35 dB, IRN of , out-of-band IIP3 of 10 dBm. It consumes 24 mA at 1.2 V power supply.
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