on chip LDO with adaptive control

Low-dropout linear regulators (LDOs) have gained popularity with the growth of battery-powered equipment. Portable electronic equipment including cellular telephones, laptop computers and a variety of handheld electronic devices has increased the need for efficient voltage regulation to prolong battery life. LDOs are widely built into all electronic appliances by all means not only for portable electronic devices. Recently, in order to save power consumptions, a system that was originally supplied by one LDO is divided into many blocks and supplied by a plurality of LDO. This means that the power is supplied only to an operating block and unused blocks are made into a standby mode. So the power consumption can be saved for a full system

 

In this work, a quick response circuit is proposed to improve the load transient response of a fully On Chip Low Dropout Voltage Regulator, which is operable with very low power consumption for use in digital baseband of cell phones was developed. The quick response circuit consists of two high speed offset comparators working in tandem with respect to the load variations. The high speed comparators were incorporated into the fast path of the circuit thereby making the fast path loop adaptive to the changes in the load transient. This was a major reason we could reduce the power consumption as the fast path was connected to the circuit only when there is a change in the load variations. The stability of the system was ensured by compensating the circuit at no load conditions. The circuit was made temperature and process independent by the use of an advanced bias circuit. The circuit was designed for a specification of 1.2V, 50mA. A line and load regulation of 30ppm/mA and 0.01% respectively was achieved. The transient overshoots and undershoots were in the range of few tens of millivolts. The circuit was satisfactorily working for temperature ranges from -55oC – 125oC. This makes the circuit comparable to the industry standards. The work was carried on CADENCE Spectre simulations with 180nm UMC CMOS technology and it showed that transient responses with less transients overshoots and undershoots, when driving large current loads, could be achieved. for more information click  link

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