Transformer-coupled input buffer for frequency synthesis

A frequency synthesis circuit, comprising:

• a first inductor having a first terminal coupled to receive a first input signal at an input frequency and having a second terminal;
• a second inductor having a second terminal coupled to receive a second input signal at the input frequency and out-of-phase relative to the first input signal, the second inductor having a second terminal;
• a first transistor having a first terminal, a second terminal coupled to a common terminal, and a control terminal coupled to the second terminal of the first inductor;
• a second transistor having a first terminal, a second terminal coupled to the common terminal, and a control terminal coupled to the second terminal of the second inductor;
• a first resonant tank comprising an inductor and a capacitor coupled in parallel between a power supply terminal and the first terminal of the first transistor, the first resonant tank tuned to a selected harmonic of the input frequency;
• a second resonant tank comprising an inductor and a capacitor coupled in parallel between the power supply terminal and the first terminal of the second transistor, the second resonant tank tuned to the selected harmonic of the input frequency;
• and
• an injection-locked oscillator having inputs coupled to the first terminals of the first and second transistors.

A circuit, comprising:

• a first transistor having a first terminal, a second terminal, and a control terminal;
• a second transistor having a first terminal, a second terminal, and a control terminal;
• a first inductor having a first terminal, and having a second terminal coupled to the first terminal of the first transistor;
• a first capacitor having a first terminal coupled to the first terminal of the first inductor, and having a second terminal coupled to the first terminal of the first transistor;
• a second inductor having a first terminal, and having a second terminal coupled to the first terminal of the second transistor;
• a second capacitor having a first terminal coupled to the first terminal of the second inductor, and having a second terminal coupled to the first terminal of the second transistor;
• a third inductor coupled between a first input and the control terminal of the first transistor;
• a fourth inductor coupled between a second input and the control terminal of the second transistor.