TH35630B - Power amplifiers and methods for supplying power at certain required output power levels. - Google Patents

Abstract

DC60 (06/05/53) This invention provides a method and device for supplying power to loads at a number of different power levels. The method includes the transition between the high and low output power of a power amplifier when amplifying a signal with a mutual modulation scheme. The bias applied to the power amplifier at the low output power is different from the bias applied to the power amplifier at the high output power. The output of the power amplifier is loaded with an impedance at the low output power different from the impedance loaded at the output of the power amplifier at the high output power. In at least one convolution, the power amplifier will transition between high and low output power at different threshold levels depending on whether the power amplifier is supplied from a high output power to a low output power or from a low output power to a high output power. This invention provides a method and device for supplying power to loads at a number of different power levels. The method includes the transition between the high and low output power of a power amplifier when amplifying a signal with a mutual modulation scheme. The bias applied to the power amplifier at the low output power is different from the bias applied to the power amplifier at the high output power. The output of the power amplifier is loaded with an impedance at the low output power different from the impedance loaded at the output of the power amplifier at the high output power. The output of a power amplifier, at least in one aspect, will fluctuate between high and low output power at different threshold levels depending on whether the amplifier is moving from a high output power to a low output power, or from a low output power to a high output power.

Claims (16)

1. The method in power amplifiers involves the transition between the high and low power outputs of the power amplifier when amplifying a signal with co-modulation. A different bias is applied to the low-power output of the power amplifier than to the bias applied to the high-power output, and the output of the power amplifier is loaded with an impedance at the low-power output that differs from the impedance loaded at the high-power output. The transition between the high and low power outputs of the power amplifier occurs at different threshold levels depending on whether the power amplifier transitions from a high-power output to a low-power output or from a low-power output to a high-power output. 2. Methods in power amplifiers that involve switching between the high and low power outputs of the power amplifier when amplifying a signal with co-modulation. This includes applying a different bias to the power amplifier at the low power output compared to the bias applied to the power amplifier at the high power output, and loading the power amplifier output with an impedance at the low power output that differs from the impedance loaded at the power amplifier output at the high power output. The differential biases applied to the power amplifier include a decreasing bias applied to the power amplifier output relative to the bias applied at the high power output, and the loading of the power amplifier output with differential impedances includes an increasing impedance applied to the power amplifier at the low power output relative to the impedance applied at the high power output. 3. Methods in power amplifiers with high and low output power within their operating range include switching between the high and low output power of the power amplifier; applying a reduced bias to the power amplifier at the low output power compared to the bias applied to the power amplifier at the high output power; and applying an increased load to the power amplifier output when operating at the low output power compared to the load applied to the power amplifier output when operating at the high output power. 4. The method under claim 3, where the transition between high-power and low-power outputs of the power amplifier appears at different threshold levels depending on whether the power amplifier switches from high-power to low-power output or from low-power to high-power output. 5. The method under claim 3, where the switching between the high-power and low-power outputs of the power amplifier involves the detection of the value of the input signal received by the power amplifier, and the switching between the high-power and low-power outputs of the power amplifier depends on the detected value of the input signal received by the power amplifier. 6. Methods for managing high and low output power in power amplifiers within their operating range include: reducing the power consumption of the power amplifier by applying a reduced bias to the amplifier when operating at low output power compared to the bias applied to the amplifier at high output power; reducing the level to which the bias can be reduced when operating at low output power within the power amplifier's operating range by increasing the impedance of the load applied to the power amplifier's output when operating at low output power compared to the load applied to the power amplifier's output when operating at high output power. 7. A power amplifier circuit comprises a power amplifier with output power levels of both high and low within the operating range of the power amplifier circuit; a variable bias circuit is connected to the power amplifier circuit, which has at least the first and second types of power amplifier bias morphology; and a variable impedance circuit is connected to the output of the power amplifier. This variable impedance circuit has at least the first and second types of power amplifier impedance morphology, where the power amplifier is morphed in a downbiased morphology at the low output power level compared to the power amplifier bias morphology at the high output power level, and the power amplifier is loaded with an impedance that increases the output power level compared to the load of the power amplifier at the high output power level. 8. Power amplifier circuit according to claim 7, where the variable bias circuit has a bias control input connected to one of the power amplifier inputs, and the variable impedance circuit has an impedance control input connected to the power amplifier input. 9. The power amplifier circuit under claim 7 is further incorporated with a controller whose control output is connected to a variable bias circuit and a variable impedance circuit, where the controller is adjusted for the configuration of the variable bias and variable impedance circuits depending on the desired power amplifier output signal. 10. A power amplifier circuit under claim 9, where a variable impedance circuit is incorporated with a switched impedance element, and where the controller is adjusted for circuit shaping, the variable impedance is achieved by exciting such switch at different output power levels of the power amplifier depending on whether the power amplifier is switched from a high to a low output power level or from a low to a high output power level. 11. The power amplifier circuit under claim 7, which also incorporates a hysteretic comparison circuit for determining when the power amplifier transitions between low and high output power levels. 12. The power amplifier circuit for supplying power to a load covers an amplified range that includes a predetermined set of desired output power levels, each desired output power level being a subset of that amplified range. Such a power amplifier circuit comprises a power amplifier with a first input for receiving the signal to be amplified, a second input for receiving the bias signal, and an output for producing the amplified signal; a control circuit including a bias adjustment circuit and an impedance selection circuit; a signal input for selecting one of the desired output levels and for producing the control signal; bias adjustment and impedance selection control signals; a variable impedance circuit connected to the output of the power amplifier and an impedance selection circuit for the control circuit. The variable impedance circuit includes several impedance states that can be selected independently, each impedance state corresponding to at least a certain range of the desired output power level; and a variable power source connected to the power amplifier. The bias adjustment circuit of the control circuit receives the bias adjustment control signal and supplies the adjusted bias signal to the second input of the power amplifier, where each predefined output power level is a range of desired output power levels, and parts of each desired output power level range overlap with parts of other desired output power level ranges in the predefined output power level series. The control circuit includes a processor connected to the bias adjustment circuit and the impedance selection circuit, which includes a processor and a storage unit connected to such processor for storing one or more sets of instructions for execution by that processor, including pre-stored instructions for receiving a new desired output power level and comparing that new desired output power level to the currently selected range of desired output power levels; pre-stored instructions for selecting the new desired output power level range, which includes the new desired output power level if the currently selected range of desired output power levels does not include the new desired output power level; and pre-stored instructions for generating the impedance selection control signal. The selection of the impedance of a variable impedance network and for generating control signals; the bias signal for adjusting the bias signal generated by the variable source to match the newly selected range of the desired output power level. 13. A power amplifier circuit for supplying power to a load covers an amplified range that includes a set of predetermined desired power output levels, each desired output power level being a subset of that amplified range. The power amplifier circuit consists of a power amplifier with a first input for receiving the signal to be amplified, a second input for receiving the bias signal, and an output for producing the amplified signal; a control circuit with a bias adjustment circuit and an impedance selection circuit for receiving the signal, which selects one of the desired output power levels, and for producing the bias adjustment and impedance selection control signals; a variable impedance circuit connected to the output of the power amplifier and the impedance selection circuit of the control circuit. The variable impedance circuit includes several selectable impedance states, each impedance state corresponding to at least a certain range of the desired output power level; and a variable power source connected to the power amplifier and bias adjustment circuit. The control circuit receives the bias adjustment control signal and supplies the adjusted bias signal to the second input of the power amplifier. The control circuit includes a processor connected to the bias adjustment circuit and the impedance selection circuit. This processor also includes a storage unit connected to it for storing one or more sets of instructions to be executed. These instructions include pre-stored commands for obtaining a new desired output power level and comparing that new level to the currently selected required output power level; pre-stored commands for generating the impedance selection control signal for a variable impedance network; and for the bias control signal product for adjusting the bias signal generated by the variable source to match the newly selected required output power level. If the newly selected required output power level is not significantly equal to the new required output power level, the signal is adjusted accordingly. 14. A method for supplying power to a load through a power amplifier circuit covering an extended range, consisting of: determining a set of desired output power levels, each output power level being a subset of the extended range; linking the bias signal level and output impedance to each desired output power level; selecting the desired output power level; adjusting the bias signal level corresponding to the selected desired output power level; selecting the output impedance corresponding to the selected desired output power level; receiving the signal to be amplified; and amplified by the received signal. When a new desired output power level is selected, if the new desired power level is higher than the previous one, the bias current is increased and a lower output impedance is selected; and if the new desired power level is lower than the previous one, the bias current is decreased and a higher output impedance is selected. 15. A method for supplying power to a load through a power amplifier circuit covering an amplified range consists of: defining a set of desired output power levels, each output power level being a subset of the amplified range; linking the bias and output impedance levels to each desired output power level; selecting the desired output power level; adjusting the bias level corresponding to the selected desired output power level; selecting the output impedance corresponding to the selected desired output power level; receiving the signal to be amplified; and amplified by the received signal. Each defined desired output power level is a range of desired output power levels corresponding to a subset of the amplified range that the power amplifier circuit covers. Furthermore, defining a set of desired power levels includes defining a range of desired power levels, a portion of which overlaps with other desired output power level ranges. This method also includes selecting a new desired output power value. The new required output power value is compared to the currently selected range of the desired output power level. If the new required output power value is not included within the currently selected range of the desired output power level, a new range of the desired output power level that includes the new required output power value is selected. The bias signal level is then adjusted, and the output impedance corresponding to the newly selected range of the desired output power level is selected. 16. A method for supplying power to a load through a power amplifier circuit covering an extended range, consisting of: determining a set of desired output power levels, each output power level being a subset of the extended range; linking the bias signal level and output impedance to each desired output power level; selecting the desired output power level; adjusting the bias signal level corresponding to the selected desired output power level; selecting the output impedance corresponding to the selected desired output power level; receiving the signal to be amplified; amplified the received signal; selecting a new desired output power value; comparing the new desired output power value to the previously selected desired output power level; if the new desired output power value is not significantly different from the previously selected output power level, selecting the new desired output power level corresponding to the current new desired output power; and adjusting the bias signal level and selecting the output impedance corresponding to the new desired output power level.