A Discrete-Time Audio $\Delta\Sigma$  Modulator Using Dynamic Amplifier With Speed Enhancement and Flicker Noise Reduction Techniques

This paper proposes an architecture to enhance coding efficiency (CE) of the Delta Sigma Modulator (DSM) transmitters. In this architecture, a complex–low pass delta sigma modulator (LPDSM) is used instead of existing Cartesian–LPDSM and polar–low pass envelope delta sigma modulator (LPEDSM). Simulation results show that for Uplink long-term evolution (LTE) signal with 1.92[Formula: see text]MHz bandwidth and 7.8-dB peak to average power ratio (PAPR), the CE for the complex–LPDSM-based transmitter is equal to 41.7% in compare to 9.7% CE for Cartesian–LPDSM transmitter. Also, due to the resolving of noise convolution problem, the complex–LPDSM-based transmitter baseband part needs lower oversampling ratio (OSR) and clock speed than polar–LPEDSM transmitter baseband part to achieve the same signal-to-noise and distortion ratio (SNDR). In the next step, a quantization noise reduction loop is implemented in this architecture. By using this technique for an Uplink LTE signal with 1.92[Formula: see text]MHz bandwidth, with the same PAPR and OSR of 16, the CE is improved from 41.7% to 56.1% with 40[Formula: see text]dB SNDR.

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Coding Efficiency and Bandwidth Enhancement in Polar Delta-Sigma Modulator Transmitter Using Quantization Noise Reduction and Parallel Processing Techniques

Journal of Circuits System and Computers ◽

10.1142/s0218126617500852 ◽

2017 ◽

Vol 26 (05) ◽

pp. 1750085 ◽

Cited By ~ 1

Author(s):

Nasser Erfani Majd ◽

Hassan Ghafoori Fard ◽

Abbas Mohammadi

Keyword(s):

Noise Reduction ◽

Average Power ◽

Quantization Noise ◽

Bandwidth Enhancement ◽

Coding Efficiency ◽

Clock Speed ◽

Delta Sigma Modulator ◽

Delta Sigma ◽

Low Pass ◽

Processing Techniques

This paper introduces an architecture to enhance coding efficiency (CE) and bandwidth of the delta-sigma modulator (DSM) transmitters. In this architecture a low-pass envelope DSM (LPEDSM) is used instead of the traditional Cartesian low-pass DSM (LPDSM) to reduce the quantization noise and to improve the coding efficiency. The simulation results show that for an uplink long-term evolution (LTE) signal with 1.92[Formula: see text]MHz bandwidth, 7.8[Formula: see text]dB peak-to-average power ratio (PAPR), and an oversampling ratio (OSR) of 32, the CE for the polar LPEDSM transmitter is equal to 41.72% in comparison to 9.7% CE for the Cartesian LPDSM transmitter. In the next step, the CE and bandwidth of the transmitter are improved at the same time by using the quantization noise reduction technique in the polar LPEDSM transmitter with parallel baseband. By using this combined technique in the four-branch transmitter baseband part for an uplink LTE signal with 7.68[Formula: see text]MHz bandwidth, 7.8[Formula: see text]dB PAPR, and an OSR of 32, the CE is improved from 42.59% to 55.86% with 40[Formula: see text]dB signal-to-noise-and-distortion ratio (SNDR) while the clock speed is only 61.44[Formula: see text]MHz which is four times lower than the clock speed requirement of the conventional transmitter baseband part to achieve the same SNDR.

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