Frequency modulator and magnetic resonance tomography system with a frequency modulator

Patent metadata

Field	Value
Publication number	US-9780727-B2
Application number	US-201313934183-A
Country	US
Kind code	B2
Filing date	Jul 2, 2013
Priority date	Jul 3, 2012
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A frequency modulator includes a first pair of diodes with two capacity diodes, and a second pair of diodes with two additional capacity diodes. The second pair of diodes is employed in parallel. The frequency modulator also includes a first modulator input for reception of a first modulation signal and a second modulator input for reception of a symmetrical second modulation signal. Both pairs of diodes are coupled to an oscillator unit.

First claim

The invention claimed is:

1. A frequency modulator for providing a communication signal that is frequency-modulated, the frequency modulator comprising:
a first modulator input for a first modulation signal for specification of a frequency modulation for the communication signal;
a second modulator input for a second modulation signal symmetrical to the first modulation signal;
an oscillator unit coupled with the first modulator input, the oscillator unit being configured, dependent on the first modulation signal and the second modulation signal, to generate the frequency-modulated communication signal at an oscillator output;
a first capacitive pair of elements with two serially connected capacity elements, a first element of the first capacitive pair of elements being coupled to the oscillator unit and a second element of the first capacitive pair of elements being coupled to a reference potential, wherein a first node between the two serially connected capacity elements is coupled to the first modulator input so that the first modulation signal is suppliable at the first node; and
a second capacitive pair of elements connected in parallel to the first capacitive pair of elements, the second capacitive pair of elements comprising two capacity elements serially connected to each other, a third element of the second capacitive pair of elements being coupled to the oscillator unit via a first coupling capacitor and a fourth element of the second capacitive pair of elements being coupled to the reference potential via a second coupling capacitor, wherein a second node between the two capacity elements of the second capacitive pair of elements is coupled to the second modulator input, so that the second modulation signal is suppliable at the second node,
the first coupling capacitor between the third element of the second capacitive pair of elements and both of the first element of the first capacitive pair of elements and the oscillator unit, and the second coupling capacitor between the fourth element of the second capacitive pair of elements and both the second element of the first capacitive pair of elements and the reference potential.

2. The frequency modulator as claimed in claim 1 , wherein at least one of the two serially connected capacity elements of the first capacitive pair of elements, at least one of the two capacity elements of the second capacitive pair of elements, or the at least one of the two serially connected capacity elements of the first capacitive pair of elements and the at least one of the two capacity elements of the second capacitive pair of elements are formed by capacity diodes.

3. The frequency modulator as claimed in claim 2 , wherein both of the two serially connected capacity elements of the first capacitive pair of elements are respectively formed by a capacity diode,
wherein the two serially connected capacity diodes of the first capacitive pair of elements are reverse-connected to each other, and
wherein both of the two capacity elements of the second capacitive pair of elements are formed by respective capacity diodes that are reverse-connected to each other and are connected to the oscillator unit with a reverse polarity to the capacity diodes of the first capacitive pair of elements.

4. The frequency modulator as claimed in claim 1 , wherein the two serially connected capacity elements of the first capacitive pair of elements and the two capacity elements of the second capacitive pair of elements are components of the same type.

5. The frequency modulator as claimed in claim 4 , wherein the components comprise diodes.

6. The frequency modulator as claimed in claim 1 , wherein the first capacitive pair of elements is coupled to the second capacitive pair of elements via at least one coupling capacitor.

7. The frequency modulator as claimed in claim 1 , further comprising a supply device operable to provide a bias voltage to individual capacity elements of the two serially connected capacity elements of the first capacitive pair of elements, to individual capacity elements of the two capacity elements of the second capacitive pair of elements, or to a combination thereof.

8. The frequency modulator as claimed in claim 7 , wherein the two capacity elements of the second capacitive pair of elements are configured as capacity diodes that are connected to the second node via anodes, and the supply device is configured to supply an electrical bias potential to cathodes of the capacity diodes, the third element of the second capacitive pair of elements coupled to the supply device via a first resistor at a node between the third element of the second capacitive pair of elements and the first coupling capacitor, and the fourth element of the second capacitive pair of elements coupled to the supply device via a second resistor at a node between the fourth element of the second capacitive pair of elements and the second coupling capacitor.

9. The frequency modulator as claimed in claim 7 , wherein the supply device is configured to supply an electrical input potential at the first modulator input and at the second modulator input.

10. The frequency modulator as claimed in claim 9 , wherein the electrical bias potential is twice as high as the electrical input potential.

11. A magnetic resonance tomography system comprising:
a frequency modulator for providing a communication signal that is frequency-modulated, the frequency modulator comprising:
a first modulator input for a first modulation signal for specification of a frequency modulation for the communication signal;
a second modulator input for reception of a second modulation signal symmetrical to the first modulation signal;
an oscillator unit coupled with the first modulator input, the oscillator unit comprising an LC-oscillating circuit configured, dependent on the first modulation signal and the second modulation signal, to generate the frequency-modulated communication signal at an oscillator output;
a first capacitive pair of elements with two serially connected capacity elements, a first element of the first capacitive pair of elements being coupled to the oscillator unit and a second element of the first capacitive pair of elements being coupled to a reference potential, wherein a first node between the two serially connected capacity elements is coupled to the first modulator input so that the first modulation signal is suppliable at the first node; and
a second capacitive pair of elements connected in parallel to the first capacitive pair of elements, the second capacitive pair of elements comprising two capacity elements serially connected to each other, a third element of the second capacitive pair of elements being coupled to the oscillator unit and a fourth element of the second capacitive pair of elements being coupled to the reference potential, wherein a second node between the two capacity elements of the second capacitive pair of elements is coupled to the second modulator input, so that the second modulation signal is suppliable at the second node.

12. The magnetic resonance tomography system as claimed in claim 11 , wherein at least one of the two serially connected capacity elements of the first capacitive pair of elements, at least one of the two capacity elements of the second capacitive pair of elements, or the at least one of the two serially connected capacity elements of the first capacitive pair of elements and the at least one of the two capacity elements of the second capacitive pair of elements are formed by capacity diodes.

13. The magnetic resonance tomography system as claimed in claim 12 , wherein both of the two serially connected capaci

Assignees

• Oppelt Ralph
• Siemens Ag

Inventors

• Oppelt Ralph

Classifications

• H03L7/099

  concerning mainly the controlled oscillator of the loop · CPC title

• H03B2201/0208

  the means being an element with a variable capacitance, e.g. capacitance diode · CPC title

• H03B2200/004

  including a variable capacitance, e.g. a varicap, a varactor or a variable capacitance of a diode or transistor · CPC title

• H03C3/00 Primary

  Angle modulation (H03C5/00, H03C7/00 take precedence) · CPC title

• H03C3/22 Primary

  the element being a semiconductor diode, e.g. varicap diode · CPC title