Radio frequency (RF) to digital polar data converter and time-to-digital converter based time domain signal processing receiver

Patent metadata

Field	Value
Publication number	US-10958491-B2
Application number	US-202016933485-A
Country	US
Kind code	B2
Filing date	Jul 20, 2020
Priority date	Nov 10, 2017
Publication date	Mar 23, 2021
Grant date	Mar 23, 2021

Abstract

The present disclosure includes a time-to-digital converter (TDC) based RF-to-digital (RDC) data converter for time domain signal processing polar receivers. Polar data conversion achieves better SNR tolerance owing to its phase convergence near the origin in a polar coordinate. The proposed RDC consists of a TDC for phase detection and an analog-to-digital converter (ADC) for amplitude conversion. Unlike the conversional data converter, the proposed ADC's sampling position is guided by the detected phase result from the TDC's output. This TDC assisted data-converter architecture reduces the number of bits required for the ADC. In addition, oversampling is no longer needed. With precisely controlled tunable delay cells and gain compensator, this hybrid data convertor is capable to directly convert Quadrature Amplitude Modulation (QAM) waveforms and Amplitude Phase Shift Keying (APSK) waveforms directly from the RF signal without down-conversion. Thus, the proposed RDC architecture achieves lower power consumption and better performance comparing with conventional I/Q receivers.

First claim

What is claimed is:

1. A polar analog-to-digital conversion method utilizing a time-to-digital based hybrid polar data converter (converter), comprising:
approximately aligning a local clock phase by selecting a closest phase generated from a multi-phase local clock synthesis block based on a digital baseband provided feedback signal;
finely aligning the local clock phase by adjusting a tunable temporal delay cell based on the digital baseband provided feedback signal for the approximate alignment;
adjusting a tunable delay in a low power analog-to-digital converter (ADC) path based on an up and low threshold values setting of a hysteresis buffer;
detecting a time from the local clock rising edge using a time-to-digital converter (TDC) block obtained in the aligning steps to a rising zero-crossing point and a falling zero-crossing point of a received signal, and converting the time into digital codes;
adjusting an ADC sample position by adjusting the tunable delay based on an output of the TDC and selecting one signal delay path based on a position of the received signal's rising and falling zero-crossing points.

2. The conversion method according to claim 1 , comprising:
adjusting a sampling clock of the ADC to the desired sampling position based on the TDC's output with the tunable temporal delay cell.

3. The conversion method according to claim 2 , further comprising selecting with a multiplexer one of two signals passing through two delay paths based on a choice of rising or falling zero-crossing point, wherein the two paths of signal delay are in the ADC path, one including a one and ¼ cycle temporal delay corresponding to the falling zero-crossing point detection of the TDC, and the other one including ¾ cycle temporal delay corresponding to the rising zero-crossing point detection of the TDC.

4. The conversion method according to claim 3 further comparing, calculating a compensation gain based on the ADC sample position in a symbol period and a pulse shape filter profile parameters to restore a nonfiltered signal with time domain signal processing.

Assignees

• Univ Auburn

Inventors

• Dai Fa
• Wang Hechen

Classifications

• H03D3/006 Primary

  by sampling the oscillations and further processing the samples, e.g. by computing techniques (H03D3/007 takes precedence) · CPC title

• H04L27/22 Primary

  Demodulator circuits; Receiver circuits · CPC title

• H04L7/0079

  Receiver details · CPC title

• H03L7/08

  Details of the phase-locked loop · CPC title

• H04B1/00

  Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission · CPC title