Ahmed Mohamed Abdelatty Ali

A 16-bit 250-MS/s IF Sampling Pipelined ADC With Background Calibration

This paper describes a 16-bit 250 MS/s ADC fabricated on a 0.18 BiCMOS process. The ADC has an integrated input buffer with a new linearization technique that improves its distortion by 5-10 dB and lowers its power consumption by 70% relative to the state of the art. It demonstrates a new background calibration technique to correct the residue amplifier (RA) gain errors and lower its power consumption. This summing node sampling (SNS) calibration technique is based on sampling the summing-node voltage of the residue amplifier and using it with the corresponding residue to estimate the amplifier open loop gain. The ADC achieves an SNDR of 76.5 dB and consumes 850 mW from a 1.8 V supply, while the input buffer consumes 150 mW from a 3 V supply. Up to 125 MS/s, the SFDR is greater than 100 dB for input frequencies up to 100 MHz and 90 dB up to 300 MHz input frequency. At 250 MS/s, the SFDR is greater than 95 dB up to 100MHz and 85 dB up to 300 MHz.

A 16b 250MS/s IF-sampling pipelined A/D converter with background calibration

Wireless communication applications have driven the development of high-resolution A/D converters (ADCs) with high sample rates, good AC performance and IF sampling capability to enable wider cellular coverage, more carriers, and to simplify the system design. We describe a 16b ADC with a sample rate up to 250MS/s that employs background calibration of the residue amplifier (RA) gain errors. The ADC has an integrated input buffer and is fabricated on a 0.18µm BiCMOS process. When the input buffer is bypassed, the SNR is 77.5dB and the SFDR is 90dB at 10MHz input frequency. With the input buffer, the SNR is 76dB and the SFDR is 95dB. The ADC consumes 850mW from a 1.8V supply, and the input buffer consumes 150mW from a 3V supply. The input span is 2.6Vp-p and the jitter is 60fs.

A 100-dB SFDR 80-MSPS 14-Bit 0.35-

This paper describes a 14-bit 80-MSPS ADC with 100-dB SFDR at 70-MHz input frequency in a 0.35-mum single-well BiCMOS technology drawing 1.2 W from a dual 3.3 V/5.0 V supply. Key barriers to high dynamic range in pipeline ADCs at high clock rates and some methods to overcome these barriers will be presented. These methods include a sampling front-end without the use of a designated Sample and Hold (S/H). A BiCMOS switching input buffer is used along with the strategic use of BiCMOS design techniques. Also, calibration is combined with capacitor shuffling to maximize linearity with minimal noise impact

muhbox m

We describe a 14-bit 1GS/s pipelined ADC that relies on correlation-based background calibration to correct the inter-stage gain, settling (dynamic) and memory errors. An effective dithering technique is embedded in the calibration signal to break the dependence of the calibration on the input signal amplitude. In addition, to improve the sampling linearity, the ADC employs input distortion cancellation and another digital calibration to compensate for the non-linear charge injection (kickback) from the sampling capacitors on the input driver. The ADC is fabricated in a 65nm CMOS process and has an integrated input buffer. With a 140MHz and 2Vpp input signal, the SNR is 69dB, the SFDR is 86dB, and the power is 1.2W.

BiCMOS Pipeline ADC

This paper describes a 14-bit, 125 MS/s IF/RF sampling pipelined A/D converter (ADC) that is implemented in a 0.35 mum BiCMOS process. The ADC has an input switched buffer and 11 pipeline stages. The sample-and-hold circuit is integrated in the first pipeline stage, which removes the need for a dedicated sample-and-hold amplifier. Measured results on silicon indicate the highest performance to date (in SNR, SFDR, DNL and INL) at this sample rate and over the whole input frequency range up to 500 MHz. The ADC achieves a DNL of less than 0.2 LSB and INL of less than 0.5 LSB. The SNR is 75 dB below Nyquist, 73 dB at 300 MHz, and 72 dB at 400 MHz. The SFDR is 100 dB below Nyquist, 89 dB at 300 MHz, and 82 dB at 400 MHz. This is also the first ADC to achieve 14-bit level performance for input signal frequencies up to 500 MHz and to have a jitter of only 50 fs

29.3 A 14b 1GS/s RF sampling pipelined ADC with background calibration

We describe a 14-bit 2.5GS/s non-interleaved pipelined ADC that relies on correlation-based background calibrations to correct the inter-stage gain, settling (dynamic), kick-back and memory errors. A new technique is employed to inject a large dither signal on the input to dither the non-linear kick-back on the ADC driver, and another large dither signal is injected to dither any residual non-linearity in the pipeline. In order to correct the effect of aging on the comparators, a new background calibration technique is employed to correct the comparator offsets. The ADC is fabricated as a dual in a 28nm CMOS process. An optional interleaved mode is provided, where the two ADCs on chip are time-interleaved to obtain a single 14-bit 5GS/s ADC. Background calibration of offset and gain mismatch and fixed calibration of timing mismatch between the two channels are implemented on chip.

A 14-bit 125 MS/s IF/RF sampling pipelined A/D converter

The cellular infrastructure market requires high clock rate, high dynamic range ADCs to enable efficient, advanced architecture receive channels. This paper describes a 14 bit 80MSPS ADC with 100dB+ SFDR at baseband in 0.35/spl mu/m BiCMOS technology using 1.1 watts on a 3.3V/5.0V dual supply. Some challenges associated with high spurious free dynamic range at high clock rates will be discussed along with methods used in this ADC to overcome these barriers.

A 14-bit 2.5GS/s and 5GS/s RF sampling ADC with background calibration and dither

High speed data converters represent one of the most challenging, important and exciting analog and mixed-signal systems. They are ubiquitous in our modern and highly connected world. Understanding and designing this class of converters require proficiency in analog circuit design, digital design, and signal processing. This book covers high speed data converters from the perspective of a leading high speed ADC designer and architect, and with a strong emphasis on high speed Nyquist A/D converters. Topics covered include an introduction to high-speed data conversion; performance metrics; data converter architectures; sampling; comparators; amplifiers; pipelined A/D converters; time-interleaved converters; digitally assisted converters; evolution and trends The book is intended for engineers and students who design, evaluate or use high speed data converters. A basic foundation in circuits, devices and signal processing is required. The book is meant to bridge the gap between analysis and design, theory and practice, circuits and systems. It covers basic analog circuits and digital signal processing algorithms. There is a healthy dose of theoretical analysis in this book, combined with the practical issues and intuitive perspectives.

A 100dB+ SFDR 80MSPS 14 bit 0.35/spl mu/m BiCMOS pipeline ADC

This paper describes the design approach and trade-offs in designing high-speed and high performance pipelined A/D converters in CMOS and BiCMOS processes. Design techniques to improve the linearity, lower the noise and reduce the power consumption will be discussed. The discussion will be in the context of a 16-bit 250 MS/s ADC fabricated on a 0.18 μm BiCMOS process. The ADC achieves an SNDR of 76.5 dB and consumes 850 mW from a 1.8 V supply, with an input buffer that consumes 150 mW from a 3 V supply. The measured SFDR is greater than 100 dB for input frequencies up to 100 MHz and 90 dB up to 300 MHz input frequency.