Xiangtao Li

An 8-bit, 12 GSample/sec SiGe track-and-hold amplifier

We present the design and implementation of an ultra-high-speed SiGe BiCMOS track-and-hold amplifier (THA) for use in high-speed analog-to-digital converters. The use of a degeneration inductor in the input buffer significantly improves the performance of the THA. The THA was fabricated in a commercially-available 0.25 /spl mu/m 200 GHz SiGe HBT BiCMOS process technology. The circuit occupies an area of 1.2 mm/sup 2/, and exhibits -49.5 dBc of total harmonic distortion (THD) when operated at a sampling frequency of 12.5 GHz with an input frequency of 3.0 GHz. Operating from a 3.5 V supply, the total power consumption is 0.7 W. To our knowledge, this circuit is the fastest 8-bit Si-based THA achieved to date.

A Low-Power,

A low-power, X-band low-noise amplifier (LNA) is presented. Implemented with 180 GHz silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs), the circuit occupies 780times660 mum2. The LNA exhibits a gain of 11.0 dB at 9.5 GHz, a mean noise figure of 2.78 dB across X-band, and an input third-order intercept point of -9.1 dBm near 9.5 GHz, while dissipating only 2.5 mW. The low-power performance of this LNA, together with its natural total-dose radiation immunity, demonstrates the potential of SiGe HBT technology for near-space radar applications

X

An ultra-high-speed SiGe track-and-hold amplifier (THA) using a switched-emitter-follower (SEF) configuration is presented. Operating off a +5.5 V power supply, this THA exhibits -32.4 dBc of total harmonic distortion (THD) when sampling a 10 GHz input signal at the rate of 40 GS/s, and reaches -50.5 dBc of THD when sampling a 2 GHz input at 12 GS/s. Compared to the THAs published in the literature with an operational range from 10 GS/s to 20 GS/s, the present THA demonstrates a THD comparable to the best one achieved to date to our knowledge for Si technology, with much improved high-frequency characteristics. On the other hand, in the operational range of 30 GS/s and above, the present SiGe THA still exhibits robust characteristics compared to the fastest THAs in terms of linearity, power consumption, and sampling rate.

-Band SiGe HBT Low-Noise Amplifier for Near-Space Radar Applications

An ultra-high-speed track-and-hold amplifier (THA) using a switched-emitter-follower (SEF) configuration is presented. Implemented in a commercially-available 0.18 /spl mu/m 120 GHz SiGe HBT BiCMOS technology, the THA core occupies a compact area of only 120 /spl times/ 200 /spl mu/m/sup 2/. The THA can operate at a sampling rate of 18 GS/sec with a total harmonic distortion (THD) of -32.3 dBc, and dissipates 128 mW, significantly smaller than other THAs in the literature operating at similar sampling rates.

A 40 GS/s SiGe track-and-hold amplifier

This paper presents a low-power high-speed BiCMOS track-and-hold amplifier (THA). It combines the differential switched-emitter follower of (Vorenkamp and Verdaasdonk, 1992) with the low-droop output buffer presented in (Fiocchi et al., 2000). A test implementation consumes 70 mW of total power (30 mW THA). It works up to 15 GS/s, using minimum-size HBTs in a 0.25/spl mu/m 200 GHz SiGe BiCMOS technology. At 10 GS/s and an input signal of 1 GHz, the achieved THD corresponds to 6.8 bits accuracy. To our knowledge, the present circuit is by far the fastest THA with low power consumption and high accuracy.

A 5-bit, 18 GS/sec SiGe HBT track-and-hold amplifier

An ultra-high-speed, master-slave comparator using an ECL configuration is presented. Implemented in a commercially-available 0.18 /spl mu/m 120 GHz SiGe HBT BiCMOS technology, the comparator core occupies a compact area of only 140 /spl times/ 325 /spl mu/m/sup 2/. Operating off a 3.5 V power supply, the comparator consumes 82 mW, excluding clock and output buffers. The comparator can operate at an 18 GHz sampling rate with 7.1 bits of resolution, and at a 20 GHz sampling rate with 4.9 bits of resolution. To our knowledge, this comparator achieves the highest resolution when compared to other stand-alone comparators in the literature operating at similar sampling rates.

A low-power, 10GS/s track-and-hold amplifier in SiGe BiCMOS technology

This paper presents a monolithic master-slave comparator in an ECL configuration with series-gating for ultra-high-speed medium-resolution analog-to-digital conversion. Implemented in a 200 GHz SiGe HBT technology, the complete chip die, including bondpads, is 1.731 /spl times/ 1.141 mm/sup 2/, with the comparator occupying only 0.0226 mm/sup 2/ when integrated as part of an ADC. It dissipates a total of 405 mW from a 3.5 V power supply. Operating with an input frequency of 5 GHz, the circuit can oversample up to 32 GS/s, with input sensitivity ranging from 5 mV/sub pp/ at 15 GS/s to 37 mV/sub pp/ at 32 GS/s. Operating at Nyquist, the comparator can sample up to 30 GS/s, with input sensitivity ranging from 12 mV/sub pp/ at 20 GS/s to 30 mV/sub pp/ at 30 GS/s. To our knowledge, this comparator achieves the best input sensitivity-sampling rate combination when compared with other standalone comparators in literature.

A 7-bit, 18 GHz SiGe HBT comparator for medium resolution A/D conversion

We present the first demonstration of a continuous-time, fifth-order, elliptic, gm-C low-pass active filter in 0.25 mum complementary (npn + pnp) silicon-germanium (C-SiGe) heterojunction bipolar transistor (HBT) technology. This C-SiGe technology features npn SiGe HBTs with peak fT and fmax of 170 GHz and 170 GHz, respectively, as well as pnp SiGe HBTs having fT and fmax of 90 GHz and 120 GHz, respectively. This C-SiGe active filter was implemented with Voorman transconductors (Voorman, 2000) to fully exploit the complementary high-speed npn and pnp SiGe HBTs. The circuit occupies an area of 0.82 mm2, and exhibits a filter cut-off frequency of 4.1 GHz. This C-SiGe active filter achieves a record continuous tuning range between 70 MHz and 4.1 GHz, attains an output noise power spectrum density (PSD) of -143 dBm/Hz, and operates off a 3.5 V supply, with a total power consumption of 100 mW at the maximum bandwidth of 4.1 GHz