Mixer circuit configuration
View Patent ↗A circuit configuration for mixing a differential desired signal with a differential local oscillator signal includes two difference amplifiers which are controllable on the input side by the desired signal and cross-coupled on the output side. Currents flowing through the difference amplifiers are switched by the components of the local oscillator signal in alternation. The circuit makes a lower supply voltage possible, given the presence of only two transistor levels.
1. A circuit configuration for mixing a desired signal with an oscillator signal, comprising:
terminals for the desired signal to be supplied with a first signal component and a complementary second signal component of the desired signal;
terminals for the oscillator signal to be supplied with a first signal component and a complementary second signal component of the oscillator signal;
first and second difference amplifiers each including a coupling node and first and second branches, said branches each having first and second terminals and a transistor;
resistors each having a first terminal connected to said first terminal of a respective one of said branches and a second terminal connected to a respective one of said coupling nodes, and current sources each connected between a respective one of said coupling nodes and a terminal for a reference potential;
said transistors of said first branches of said difference amplifiers having control terminals controlled by the first component of the desired signal, and said transistors of said second branches of said difference amplifiers having control terminals controlled by the second component of the desired signal;
load elements each connecting said second terminal of said first branch of one of said difference amplifiers and said second terminal of said second branch of another of said difference amplifiers together to a terminal for a supply potential; and
additional transistors each to be controlled by a respective one of the signal components of the oscillator signal, said additional transistors each connected between the terminal for the supply potential and said first terminal of a respective one of said resistors of said branches of said difference amplifiers.
2. The circuit configuration according to claim 1 , wherein said current sources are constant current sources.
3. A circuit configuration for mixing a desired signal with an oscillator signal, comprising:
terminals for the desired signal to be supplied with a first signal component and a complementary second signal component of the desired signal;
terminals for the oscillator signal to be supplied with a first signal component and a complementary second signal component of the oscillator signal;
first and second difference amplifiers each including a coupling node and first and second branches, said branches each having first and second terminals and a transistor;
resistors each having a first terminal connected to said first terminal of a respective one of said branches and a second terminal connected to a respective one of said coupling nodes, and current sources each connected between a respective one of said coupling nodes and a terminal for a reference potential, each of said current sources being a switchable current source with an impressible current to be controlled in dependence upon a respective one of the components of the oscillator signal;
said transistors of said first branches of said difference amplifiers having control terminals controlled by the first component of the desired signal, and said transistors of said second branches of said difference amplifiers having control terminals controlled by the second component of the desired signal; and
load elements each connecting said second terminal of said first branch of one of said difference amplifiers and said second terminal of said second branch of another of said difference amplifiers together to a terminal for a supply potential.
4. The circuit configuration according to claim 3 , including capacitive elements each connected between one of said terminals for the oscillator signal and the control terminal of a respective one of said transistors of said difference amplifiers, said coupling nodes of said first and second difference amplifiers being in the form of a shared common coupling node.
5. The circuit configuration according to claim 3 , wherein said load elements each have difference amplifiers and first and second branches, additional load elements are each connected between a respective one of said first branches and the terminal for the supply potential, said second branches have load sides coupled to each other and connected to the terminal for the supply potential, and said first and second branches are jointly controllable by respective control signals.
6. The circuit configuration according to claim 3 , wherein said current sources of said difference amplifiers are formed by a common current source connecting said coupling node to the terminal for the reference potential.