A Power Efficient Audio Amplifier Combining Switching and Linear Techniques

Integrated Class D audio amplifiers are very power efficient, but require an external filter which prevents further integration. Also due to this filter, large feedback factors are hard to realise, so that the load influences the distortion- and transfer characteristics. The amplifier presented in this paper consists of a switching part that contains a much simpler filter, and a linear part that ensures a low distortion and flat frequency response. A 30W version was realised. The switching part of the amplifier was integrated in a BCD process. Together with a linear part and with a loudspeaker as load, it has a flat frequency response +/- 0.3dB, a dissipation that is up to 5 times lower than a traditional class AB audio amplifier, and a distortion of <0.02% over power and frequency range

A 0.1-to-1.2GHz tunable 6th-order N-path channel-select filter with 0.6dB passband ripple and +7dBm blocker tolerance

Radio receivers should be robust to large out-of-band blockers with small degradation in their sensitivity. N-path mixers can be used as mixer-first receivers [1] with good linearity and RF filtering [2]. However, 1/f noise calls for large active device sizes for IF circuits and high power consumption. The 1/f noise issue can be relaxed by having RF gain. However, to avoid desensitization by large out-of-band blockers, a bandpass filter (BPF) with sharp cut-off frequency is required in front of the RF amplifiers. gm-C BPFs suffer from tight tradeoffs among DR, power consumption, Q and fc. Also, on-chip Q-enhanced LC BPFs [3] are not suitable due to low DR, large area and non-tunability. Therefore, bulky and non-tunable SAW filters are used. N-path BPFs offer high Q while their center frequency is tuned by the clock frequency [2]. Compared to gm-C filters, this technique decouples the required Q from the DR. The 4-path filter in [4] has only 2nd-order filtering and limited rejection. The order and rejection of N-path BPFs can be increased by cascading [5], but this renders a “round” passband shape. The 4th-order 4-path BPF in [6] has a “flat” passband shape and high rejection but a high NF. This work solves the noise issue of [6] while achieving the same out-of-band linearity and adding 25dB of voltage gain to relax the noise requirement of the subsequent stages

Low power radio communication platform for wireless sensor network

Wireless sensor networks are predicted to be the most versatile, popular and useful technology in the near future. A large number of applications are targeted which will hugely benefit from a network of tiny computers with few sensors, radio communication platform, intelligent networking and controller programs. Few of these applications which look very attractive at this point of time are medical (such as patient monitoring), structure monitoring (such as bridges, coal mine), logistics and transport, control and rescue operation in natural hazards (like firefighters), building management (security, temperature control), wild life/ ocean life monitoring, traffic control, area monitoring, intruder tracking etc

A wideband supply modulator for 20MHz RF bandwidth polar PAs in 65nm CMOS

A wideband modulator for a 20MHz bandwidth polar modulated PA is presented which achieves a maximum efficiency of 87.5% and a small signal -3dB bandwidth of 285MHz. Realized in 65nm CMOS, it consists of a cascoded nested Miller compensated linear amplifier and a class D switching amplifier. It can deliver 22.7dBm output power to a 5.3Ω load. With a switching frequency of 118MHz, the output switching ripple is 4.3mVrms. Keywords: supply modulator, power amplifier, CMOS and cascoded nested Miller

Flip-Flops for accurate multiphase clocking: transmission gate versus current mode logic

Dynamic transmission gate (DTG) flip-flops (FFs) (DTG-FFs) and current mode logic (CML) FFs (CML-FFs) are compared targeting power efficient multiphase clock generation with low phase error. The effect of component mismatches on multiphase clock timing inaccuracies is modeled and compared, using the product of mismatch-induced jitter variance and power consumption as a figure-of-merit (FOM). Analytical equations are derived to estimate the jitter–power FOM for DTG-FF- and CML-FF- based dividers. Simulations confirm the trends predicted by the equations and show that DTG-FFs achieve a better FOM than CML-FFs. The advantage increases for CMOS processes with smaller feature size and for a lower input frequency compared to $f_T$

Frequency Compensation of an Audio Power Amplifier

Abstract— A car audio power amplifier is presented that uses a frequency compensation scheme which avoids large\ud compensation capacitors around the MOS power transistors,\ud while retaining the bandwidth and stable load range of nested miller compensation. THD is 0.005%@(1kHz, 10W), SNR is 108dB, and the amplifier is stable for any passive load up to 50nF

Frequency Compensation of an SOI Bipolar-CMOS-DMOS Car Audio PA

A car audio PA uses a frequency-compensation scheme that avoids large compensation capacitors while retaining the bandwidth and stable load range of nested Miller compensation. The THD is 0.005% at 1kHz and 10W output power. The SNR is 108dB and the amplifier is stable for any passive load up to 50nF. The PA is fabricated in a 1µm SOI bipolar-CMOS-DMOS process

Analysis of a 1kbps Backscatter Receiver with up to -80dBm Tag-to-tag Receive Sensitivity

Merging developments in RFID and wireless sensor networks have increased the interest in using backscatter radio for tag-to-tag communication. Low power consumption is a major concern, often limiting the choice to incoherent receivers such as diode envelope detectors. Link budget calculations require receiver sensitivity specifications, however accurate characterizations are scarce. In this work, we show that the receiver sensitivity is strongly related to the exciter incident power. Full-range analysis of a zero-bias diode detector shows a decreasing noise factor at higher incident powers, which leads to improved sensitivity. On the other side, at strong incident powers, the phase noise of the exciter interferes with the received signal, setting an lower bound to the sensitivity of the backscatter receiver. This work proposes a semi-passive RFID tag capable of 1kbps to 10kbps data rates in the 434MHz band using off the shelf components. The tag has a low power consumption of 85μW during receive, 45μW during transmit and less than 4μW in sleep. The receiver sensitivity at 1kbps shows a 25dB variation as a function of exciter incident power between -50 to 10dBm, while a peak sensitivity of around -80dBm is measured at an incident power of -25dBm