-
公开(公告)号：GB2441358B
公开(公告)日：2011-07-06
申请号：GB0617139
申请日：2006-08-31
Applicant: WOLFSON MICROELECTRONICS PLC
Inventor： LESSO JOHN PAUL , PENNOCK JOHN LAURENCE
IPC: H02M3/155
-
公开(公告)号：GB2475636A
公开(公告)日：2011-05-25
申请号：GB201103080
申请日：2006-12-22
Applicant: WOLFSON MICROELECTRONICS PLC
Inventor： LESSO JOHN PAUL , PENNOCK JOHN LAURENCE , FRITH PETER JOHN
Abstract: The power supply 80 for an audio amplifier output stage 40 provides voltages which vary in dependence on a volume control signal S2 which controls the gain of amplifier stage 20. The power supply comprises a flying capacitor charge pump circuit (figures 5b, 16b) which provides opposite polarity supplies from a single polarity input. The charge pump may be fed through a controllable DC-DC buck converter (1010, figure 26), which can be bypassed when the battery voltage is low. The supply voltages may be regulated (figure 15). The charge pump may have dual modes (figures 10, 16b) wherein it can be controlled to provide outputs which are either equal to the input voltage or a fraction of the input voltage. Only one flying capacitor is required to provide a split supply of +/- VDD/2.
-
公开(公告)号：GB2465695A
公开(公告)日：2010-06-02
申请号：GB201000039
申请日：2007-12-28
Applicant: WOLFSON MICROELECTRONICS PLC
Inventor： LESSO JOHN PAUL
Abstract: A charge pump power supply 102 provides a supply voltage to an amplifier 16 driving a load 18, the nature of which (for example whether it is a line-out or headphones) is determined from the time taken for the charge pump output voltage to fall by a predefined amount or from the voltage drop during a predefined interval (figure 2) or from the rate of voltage droop. These parameters indicate the discharge rate of the charge pump reservoir capacitor 14 and thus provide an indication of the impedance of the load 18. Alternatively, the net charging rate of the capacitor 14 may be measured. A test signal generator is not required because the envelope detector 106 enables the decision circuit 104 to assess the impedance of the load by reference to the amplitude of the audio input signal. If the output load is determined to be a line output the signal amplitude may be raised, but if a headphone load is detected the signal amplitude may be reduced to protect the amplifier and the listener.
-
Patent Agency Ranking
公开(公告)号：GB2451530A
公开(公告)日：2009-02-04
申请号：GB0721431
申请日：2007-10-31
Applicant: WOLFSON MICROELECTRONICS PLC
Inventor： LESSO JOHN PAUL
IPC: H03F1/02
Abstract: The bias voltage or current for the amplifiers 718,705, DAC 716, or other circuit in a playback channel is adapted in dependence on the level of the input signal and/or a gain control signal such as a volume control signal (figure 14). Higher bias is applied when the signal in the channel has a high amplitude, thereby improving the noise, linearity and distortion performance of the circuits. Lower bias is applied when the signal in the channel has a low amplitude, thereby reducing power consumption. The technique may be used in portable and non-portable apparatus such as MP3 players, mobile 'phones, cameras, TVs, Hi-Fi systems or satellite navigation systems. It may also be used in entertainment systems in cars, trains or aeroplanes, or in noise-cancellation.
-
公开(公告)号：GB2451474A
公开(公告)日：2009-02-04
申请号：GB0714889
申请日：2007-07-31
Applicant: WOLFSON MICROELECTRONICS PLC
Inventor： LESSO JOHN PAUL
Abstract: A word length reduction circuit comprises an input, a word length reduction block 103, a signal processing block 111 and an adder 102. The word length reduction block 103 generates an output signal and an error signal from a modified input signal, the output signal having a smaller number of bits than the modified input signal. The signal processing block 111 comprises an unstable feedback loop and receives the error signal to generate a random dither signal. The adder 102 generates the modified input signal from the input and the random dither signal. The circuit may be used in audio and video devices.
-
公开(公告)号：GB2446843A
公开(公告)日：2008-08-27
申请号：GB0625955
申请日：2006-12-22
Applicant: WOLFSON MICROELECTRONICS PLC
Inventor： LESSO JOHN PAUL , PENNOCK JOHN , FRITH PETER JOHN
Abstract: The power supply 80 for an audio amplifier output stage 40 provides voltages which vary in dependence on a volume control signal S2 which controls the gain of amplifier stage 20. The power supply comprises a flying capacitor charge pump circuit (figures 5b, 16b) which provides opposite polarity supplies from a single polarity input. The charge pump may be fed through a controllable DC-DC buck converter (1010, figure 26), which can be bypassed when the battery voltage is low. The supply voltages may be regulated (figure 15). The charge pump may have dual modes (figures 10,16b) wherein it can be controlled to provide outputs which are either equal to the input voltage or a fraction of the input voltage. The variable power supply technique may be applied to line drivers for data transmission (figure 31).
-
公开(公告)号：GB2444988A
公开(公告)日：2008-06-25
申请号：GB0625799
申请日：2006-12-22
Applicant: WOLFSON MICROELECTRONICS PLC
Inventor： LESSO JOHN PAUL , PENNOCK JOHN , FRITH PETER JOHN
Abstract: An audio amplifier uses the same circuit to drive either low impedance loads such as headphones with 32 Ohms impedance (fig. 1a) or high impedance loads such as the input impedance of an external amplifier with 10 KOhms impedance (figs. 1b or 1c). A dual mode charge pump 10 provides lower supply voltages when the loads have low impedance. Separate amplifiers for high and low impedance loads are thus not required. The mode of operation is determined by control circuit 24. The user may select the mode by use of a switch or menu option, or by setting the volume control to full scale to select a line output. Alternatively, the load impedance or output current may be sensed, or a headphone jack socket may be distinguished from a docking station. A signal indicating docking may also control the mode. The amplifier may be disabled when a headphone is attached and volume is set to full scale. Alternatively, the amplifier output impedance may be increased in high impedance mode.
-
公开(公告)号：GB2444984A
公开(公告)日：2008-06-25
申请号：GB0625954
申请日：2006-12-22
Applicant: WOLFSON MICROELECTRONICS PLC
Inventor： LESSO JOHN PAUL , PENNOCK JOHN , FRITH PETER JOHN
IPC: H02M3/07
Abstract: Disclosed is a dual mode charge-pump circuit for providing a plurality of output voltages Vout+, Vout-, using a single flying capacitor Cf. The circuit comprises a network of switches 410 that is operable in a number of different states and a controller 420 for operating the switches 410 in a sequence of states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage +Vdd and centred on the voltage at the common terminal. The circuit may also be operated so as to generate positive and negative output voltages each up to substantially the input voltage.
-
-
-
-
-
-
-
Search Results
98
records
(took 0.028 seconds)
