A Fully Digital Delay Line Based GHz Range Multimode Transmitter Front-End in 65-nm CMOS

Nuyts, Pieter A. J.; Singerl, Peter; Dielacher, Franz; Reynaert, Patrick; Dehaene, Wim

doi:10.1109/jssc.2012.2191032

Cited by 55 publications

(23 citation statements)

References 25 publications

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“…In baseband PWM transmitters [57,[67][68][69][70][71][72], the amplitude information of the input signal is encoded into a PWM signal of frequency ω IF and mixed with a phase modulated carrier signal of frequency ω c to generate the transmit signal. Baseband PWM transmitters are also referred to as polar PWM transmitters (PPWMTs) and its block diagram is shown in Figure 3.1.…”

Section: Baseband Pwm Transmittersmentioning

confidence: 99%

All-Digital PWM Transmitters

Pasha

2019

Linköping Studies in Science and Technology. Dissertations

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Electronic devices with wireless connectivity are fast becoming a part of daily life. According to some estimates, in the next five years, 10 billion new devices with internet connectivity would be produced. To lower the costs and extend the battery life of electronic circuits, there is an increased interest in using lowcost, low-power CMOS circuits. By taking advantage of the higher integration capabilities of modern CMOS, the analog, digital, and radio circuits can be integrated on a single die, typically called a radio-frequency system-on-chip (RF-SoC). In an RF-SoC, most of the power is usually consumed by the radio circuits, especially the power amplifier (PA). Hence, to take advantage of the improved switching capability of transistors in modern CMOS, the use of switch-mode PAs (SMPAs) is becoming more popular. SMPAs exhibit a much higher efficiency as compared to their linear counterparts and can be easily integrated with the digital baseband circuits. To satisfy the demand for higher data throughput, modern wireless standards like LTE and IEEE 802.11 generate envelope-varying signals using advanced modulation schemes like M-QAM and OFDM. Among several other techniques, pulse-width modulation (PWM) allows for the amplification of the envelopevarying signals using SMPAs. The first part of this thesis explores techniques to improve the spectral performance of PWM-based transmitters. The proposed transmitters are fully digital, and the entire signal chain up to the PA can be implemented using the digital design flow, which is especially beneficial in sub-micron CMOS processes with low voltage headroom. A new transmitter is proposed that compensates for the aliasing distortion in polar PWM transmitters by using outphasing. The transmitter exhibits an improvement of up to 9 dB in dynamic range for a 1.4 MHz LTE uplink signal. The idea is extended to compensate for both image and aliasing distortions in all-digital implementations of polar PWM transmitters. By using a field programmable gate array (FPGA) and Class-D SMPAs, the proposed transmitter shows an improvement of up to 6.9 dBc in the adjacent channel leakage ratio (ACLR) and 10% in the error vector magnitude (EVM) for a 20 MHz LTE uplink signal. The proposed transmitter is fully programmable and can be easily adapted for multi-band and multi-standard transmission.

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Section: Baseband Pwm Transmittersmentioning

confidence: 99%

All-Digital PWM Transmitters

Pasha

2019

Linköping Studies in Science and Technology. Dissertations

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“…The envelope path, including a digital PWM [3] with the quantization level of 256 and IF clock f IF of 3.25 MHz, an inverter-chain based driver buffer with a perfect push-pull dead zone, a complementary power switch with low on resistor, and a 2 nd -order LC filter with a cutoff frequency of 1MHz, performs the mapping from multi-bit digital envelope to the pulse-width of the IF clock, which is then low-pass filtered to generate the analog envelope at the PA supply. The large-sized power switch consisting of complementary power transistors, works in class-D mode with 0.3ns dead zone to provide large-current driver capability for the PA supply.…”

Section: Architecturementioning

confidence: 99%

“…2 shows the proposed envelope path, employing a digital IF PWM based open-loop power switch followed by an LC filter. The principle and design of digital IF PWM, based on delay multiplexer with inverter based delay line and unit-delay auto-calibration, has been clearly clarified in [3]. By employing an L-level quantizer and an L-stage delay line with an unit delay of 1/(2L×f IF ), the multi-bit baseband envelope components are equidistantly quantized to L discrete values and mapped to L discrete rising-edge lags, and correspond to L discrete pulse-widths of the IF clock, which are lowpass filtered to reconstruct the analog envelope components at the PA supply with large-current driver capability provided by the class-D power switch.…”

Section: Design Implementationmentioning

confidence: 99%

“…The existing transmitter [3] with intermediatefrequency (IF) pulse-width modulation (PWM), is prone to low spectrum purity, especially for low carrierfrequency (CF) cases where IF interferences closer to the carrier are difficult to be eliminated only by a band-pass filter (BPF) and without any IF filter. The existing design [4] with all-digital phase-locked loop (PLL) based phase and digital delta-sigma (∆-Σ) modulator (DSM) based envelope paths, introduces large fractional spurs and requires strict energy match between power branches.…”

Section: Introductionmentioning

confidence: 99%

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Polar Transmitter with Differential DSM Phase and Digital PWM Envelope

Zhou

Liu²

2014

JSTS:Journal of Semiconductor Technology and Science

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Abstract-A low-power low-cost polar transmitter for EDGE is designed in 0.18µm CMOS. A differential delta-sigma modulator (DSM) tunes a three-terminal voltage-controlled oscillator (VCO) to perform RF phase modulation, where the VCO tuning curve is digitally pre-compensated for high linearity and the carrier frequency is calibrated by a dual-mode lowpower frequency-locked loop (FLL). A digital intermediate-frequency (IF) pulse-width modulator (PWM) drives a complementary power-switch followed by an LC filter to achieve envelope modulation with high efficiency. The proposed transmitter with 9mW power dissipation relaxes the time alignment between the phase and envelope modulations, and achieves an error vector magnitude (EVM) of 4% and phase noise of −123dBc/Hz at 400kHz offset frequency.

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“…The polar PWM transmitter (PPWMT) [62][63][64][65] have a larger dynamic range at high carrier frequency as it does not suffer from pulse swallowing in PAs [48]. In the PPWMT, the non-constant envelope signal is converted into carrier bursts of varying duration, which operate the PA in either on state achieving peak efficiency or the off state where no power consumed.…”

Section: Conceptmentioning

confidence: 99%

Pulse-Width Modulated RF Transmitters

Haque¹

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To my mother, father, and uncle (mamoo), AbstractThe market for wireless portable devices has grown significantly over the recent years. Wireless devices with ever-increased functionality require high rate data transmission and reduced costs. High data rate is achieved through communication standards such as LTE and WLAN, which generate signals with high peak-to-average-power ratio (PAPR), hence requiring a power amplifier (PA) that can handle a large dynamic range signal. To keep the costs low, modern CMOS processes allow the integration of the digital, analog and radio functions on to a single chip. However, the design of PAs with large dynamic range and high efficiency is challenging due to the low voltage headroom.To prolong the battery life, the PAs have to be power-efficient as they consume a sizable percentage of the total power. For LTE and WLAN, traditional transmitters operate the PA at back-off power, below their peak efficiency, whereas pulse-width modulation (PWM) transmitters use the PA at their peak power, resulting in a higher efficiency. PWM transmitters can use both linear and SMPAs where the latter are more power efficient and easy to implement in nanometer CMOS. The PWM transmitters have a higher efficiency but suffer from image and aliasing distortion, resulting in a lower dynamic range, amplitude and phase resolution.This thesis studies several new transmitter architectures to improve the dynamic range, amplitude and phase resolution of PWM transmitters with relaxed filtering requirements. The architectures are suited for fully integrated CMOS solutions, in particular for portable applications.The first transmitter (MAF-PWMT) eliminates aliasing and image distortions while allowing the use of SMPAs by combining RF-PWM and band-limited PWM. The transmitter can be implemented using all-digital techniques and exhibits an improved linearity and spectral performance. The approach is validated using a Class-D PA based transmitter where an improvement of 10.2 dB in the dynamic range compared to a PWM transmitter for a 1.4 MHz of LTE signal is achieved.The second transmitter (AC-PWMT) compensates for aliasing distortion by combining PWM and outphasing. It can be used with switch-mode PAs (SMPAs) or linear PAs at peak power. The proposed transmitter shows better linearity, improved spectral performance and increased dynamic range as it does not suffer from AM-AM distortion of the PAs and aliasing distortion due to digital PWM. The idea is validated using push-pull PAs and the proposed transmitter shows an improvement of 9 dB in the dynamic range as compared v vi Abstract to a PWM transmitter using digital pulse-width modulation for a 1.4 MHz LTE signal.The third transmitter (MD-PWMT) is an all-digital implementation of the second transmitter. The PWM is implemented using a Field Programmable Gate Array (FPGA) core, and outphasing is implemented as pulse-position modulation using FPGA transceivers, which drive two class-D PAs. The digital implementation offers the flexibility to adapt the transmitter...

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A Fully Digital Delay Line Based GHz Range Multimode Transmitter Front-End in 65-nm CMOS

Cited by 55 publications

References 25 publications

All-Digital PWM Transmitters

All-Digital PWM Transmitters

Polar Transmitter with Differential DSM Phase and Digital PWM Envelope

Pulse-Width Modulated RF Transmitters

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