Hong Kong Applied Science and Technology Research Institute Company, Limited

Lu Chen

Huimin Guo

Kam Chuen Wan

Yat Tung Lai

Wuxue Ni

An On-Off Shift Keying (OOK) receiver has non-continuous Automatic Gain Control (AGC) that sets gain at the beginning of each frame and locks the gain setting for the remainder of the frame, preventing OOK data from causing AGC loop instability. An AGC controller initializes to maximum the gain settings for a Low-Noise Amplifier (LNA), Low-Pass Filter (LPF), and a Programmable Gain Amplifier (PGA) in series that power a rectifier generating a voltage output to a 1/0 data decision circuit. A level detector compares the voltage output to two thresholds. When both thresholds are exceeded, the AGC controller steps down gain settings until the voltage output is between the two thresholds, when the gain settings are locked for the remainder of the current frame. A frame detector resets the AGC controller between frames when a long series of 0 data between frames is detected. LNA gain is reduced last.

Automatic Gain Control (AGC) for On-Off Shift-Keying (OOK) receiver

A hybrid Analog-to-Digital Converter (ADC) has multiple stages. A first stage and a final stage each use a Successive-Approximation Register (SAR) ADC to generate the Most-Significant-Bits (MSBs) and the Least-Significant-Bits (LSBs) over successive internal cycles. Middle stage(s) use a faster flash ADC with multiple comparators in parallel to generate the middle binary bits, which are then re-converted by a Digital-to-Analog Converter (DAC) and subtracted from the stage's input analog voltage to generate a difference that is amplified by a residual amplifier that outputs an amplified voltage to the next stage. The first stage also has this multiplying DAC structure to convert the MSBs to an amplified voltage to the first of the middle stages. Finally, digital error correction logic removes redundant binary bits between stages. Initial and final SAR stages of 4 and 8 bits with a 4-bit middle stage provide a hybrid ADC of 14-bit precision.

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Lu Chen