Abstract In a digital radio telephone transmitter an output pulse with e.g. cos²-shaped edges is produced by a voltage controlled power amplifier (1). When known control loop circuitry is used, the power (Pout) of the output pulse will rise almost step-wise at the beginning of the pulse, which leads to the spreading of the spectrum and to rise time delays of the output pulse with respect to the control pulse (TXC) at different power levels. According to the invention a good cos²-shape of the output pulse (Pout) and its tracking of the control pulse (TXC) almost without delay is achieved so that a squarewave pulse (Vp) is added to the control voltage (V2) of the power amplifier (1), the pulse (Vp) starting and ending substantially at the same time as the control pulse (TXC). In a preferred embodiment the squarewave pulse (Vp) is added to the control voltage (V2) only during that time when the control voltage (V2) is below that value, at which the the control loop begins to operate.
A method for controlling the rising and falling edges of the output pulse of a voltage controlled power amplifier (4) to track the waveform of a control pulse (TXC) when the power amplifier is controlled with a control loop producing the control voltage (V2) with the aid of a voltage (V1) proportional to the output pulse power (Pout) and with the aid of a control pulse (TXC), whose rising and falling edges are e.g. cos²-shaped, characterized in that a squarewave pulse (Vp) is added to the control voltage (V2) of the power amplifier, the pulse (Vp) starting and ending substantially at the same time as the control pulse (TXC).
Claim 2
Independent Claim
37 words
A method according to claim , characterized in that the voltage level of the squarewave pulse (Vp) is approximately the same as that value of the control voltage (V2), at which the control loop begins to operate.
Claim 3
Dependent Claim
44 words
A method according to claim 1 or 2, characterized in that the squarewave pulse (Vp) is added to the control voltage (V2) only during that time when the control voltage (V2) is below that value (V3), at which the control loop begins to operate.
Claim 4
Dependent Claim
115 words
Circuitry to control the rising and falling edges of the output pulse of a voltage controlled power amplifier (4) to track the waveform of a control pulse (TXC) when the power amplifier is controlled with a control loop producing the control voltage (V2) with the aid of a voltage (V1) proportional to the output pulse power (Pout) and with the aid of a control pulse (TXC), whose rising and falling edges are e.g. cos²-shaped, characterized in that it includes a summing circuit, in which a squarewave pulse (Vp) is added to the control voltage (V2) of the power amplifier, the pulse (Vp) starting and ending substantially at the same time as the control pulse (TXC).
Claim 5
Dependent Claim
32 words
Circuitry according to claim 4, characterized in that it includes a switching means (5) disconnecting the squarewave pulse (Vp) from the summing circuit during that time when the control loop is operating.
Claim 6
Dependent Claim
16 words
Circuitry according to claim 5, characterized in that the switching means (5) is a transistor circuit.
Claim 7
Dependent Claim
35 words
Circuitry according to claim 4, characterized in that the voltage of the squarewave pulse (Vp) is approximately the same as that value of the control voltage (V2), at which the control loop begins to operate.
Claim 8
Dependent Claim
17 words
Circuitry according to claim 4, characterized in that the summing circuit comprises summing resistors (R3 and R4).
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