Method of using integrated power amplifier
View Patent ↗An output-impedance in a power amplifier is provided. A first transistor Q BUF of a buffer stage is connected to a first side of a resistor R F and a second transistor Q AMP to a second opposite side of the resistor R F . The first transistor feeds a current I RF to the second resistor Q AMP . The current I RF at the second transistor is copied and multiplied by a factor (n) to form an output current I OUT , as (1+n)*I RF . The current I RF is fed back to the first transistor and the output current I OUT is fed to a load resistor R.
1. A method for providing an output-impedance in a power amplifier, comprising:
connecting a first transistor (Q BUF ) on a first side of a impedance (R F ) and a second transistor (Q AMP ) to a second opposite side of the impedance (R F ),
the first transistor feeding a current (I RF ) to the impedance (R F ),
copying the current (I RF ) at the second transistor,
multiplying the current with a factor (n) to form an output current (I OUT ), as (1+n)*(I RF ),
feeding back the current (I RF ) to the first transistor,
feeding the output current (I OUT ) to a load resistor (R), and
using an additional impedance (R G ) to load a buffer stage and increasing the output power without affecting any output impedance of the power amplifier.
2. The method according to claim 1 wherein the method further comprises providing a buffer stage having the first transistor Q BUF .
3. The method according to claim 2 wherein the method further comprises buffering an input voltage (V IN ) to a source voltage VS in the buffer stage.
4. The method according to claim 1 wherein the method further comprises feeding back the current (I RF ) via the impedance (R F ) to a buffer stage.
5. The method according to claim 1 wherein the method further comprises using a DC block to prevent direct current voltage from being fed to the load resistor (R).
6. The method according to claim 1 wherein the method further comprises programming the additional impedance (R G ) to gain control of an output power of the output stage.