Low pass filter and electronic device

1. A low-pass filter comprising a large and a small capacitor which are connected in parallel, the large capacitor being connected in series with a resistor, characterized in that the filter is embodied on the basis of a semiconductor substrate with a first surface, in which the small and the large capacitor are each provided as a single vertical trench capacitor, the trenches extending to the first surface on which the resistor is provided and further characterized in that the semiconductor substrate further comprises a drift compensation part.

2. A low-pass filter comprising a large and a small capacitor which are connected in parallel, the large capacitor being connected in series with a resistor, characterized in that the filter is embodied on the basis of a semiconductor substrate with a first surface, in which the small and the large capacitor are each provided as a single vertical trench capacitor, the trenches extending to the first surface on which the resistor is provided and further characterized in that the small and the large capacitor are separated by a high-ohmic substrate zone with a resistance of at least 0.5 kΩ/cm wherein the high-ohmic substrate zone is situation to mitigate leakage.

3. A low-pass filter as claimed in claim 1 , characterized in that the trench capacitors have a dielectric comprising silicon nitride.

4. A low-pass filter as claimed in claim 1 , characterized in that the resistor comprises a layer of polysilicon, in which layer the upper electrodes of the capacitors are defined as well.

5. A low-pass filter as claimed in claim 1 , characterized in that the semiconductor substrate further comprises diodes.

6. An electronic device, comprising: a phase locked loop function including a comparator, a low-pass filter and a voltage controlled oscillator, the comparator and the oscillator being part of a single semiconductor device and the low-pass filter including a large and a small capacitor that are connected in parallel, the large capacitor being connected in series with a resistor, wherein the low-pass filter is embodied on the basis of a semiconductor substrate with a first surface, in which the small and the large capacitor are each provided as a single vertical trench capacitor, the trenches extending to the first surface on which the resistor is provided and the low-pass filter being assembled to the semiconductor device in a stacked die construction, and wherein the semiconductor device is provided with a first and an opposed second side, at which first side the low-pass filter is present and at which second side the semiconductor device can be coupled to a heat sink.

7. An electronic device comprising: a phase locked loop function including a comparator, a low-pass filter and a voltage controlled oscillator, the comparator and the oscillator being part of a single semiconductor device and the low-pass filter including a large and a small capacitor that are connected in parallel, the large capacitor being connected in series with a resistor, wherein the low-pass filter is embodied on the basis of a semiconductor substrate with a first surface, in which the small and the large capacitor are each provided as a single vertical trench capacitor, the trenches extending to the first surface on which the resistor is provided and the low-pass filter being assembled to the semiconductor device in a stacked die construction, and wherein the low-pass filter has lateral dimensions which are at most equal to those of the semiconductor device.

8. An electronic device comprising: a phase locked loop function including a comparator, a low-pass filter and a voltage controlled oscillator, the comparator and the oscillator being part of a single semiconductor device and the low-pass filter including a large and a small capacitor that are connected in parallel, the large capacitor being connected in series with a resistor, wherein the low-pass filter is embodied on the basis of a semiconductor substrate with a first surface, in which the small and the large capacitor are each provided as a single vertical trench capacitor, the trenches extending to the first surface on which the resistor is provided and the low-pass filter being assembled to the semiconductor device in a stacked die construction, and the phase locked loop being provided in an open loop architecture.

9. A low-pass filter comprising a large and a small capacitor which are connected in parallel, the large capacitor being connected in series with a resistor, characterized in that the filter is embodied on the basis of a semiconductor substrate with a first surface, in which the small and the large capacitor are provided as vertical trench capacitors, the trenches extending to the first surface on which the resistor is provided, and characterized in that the small capacitor and the large capacitor are separated by a high-ohmic substrate zone with a resistance of at least 0.5 kΩ/cm.

10. A low-pass filter as claimed in claim 9 , characterized in that the semiconductor substrate further includes a drift compensation part.

11. A low-pass filter as claimed in claim 9 , characterized in that one end of the filter is connected to ground.

12. A low-pass filter as claimed in claim 9 , characterized in that the trench capacitors have a dielectric that includes silicon nitride.

13. A low-pass filter as claimed in claim 9 , characterized in that the resistor includes a layer of polysilicon, and upper electrodes of the large and small capacitors are defined in the layer of polysilicon.

14. A low-pass filter as claimed in claim 9 , characterized in that the semiconductor substrate further includes diodes.

15. A low-pass filter as claimed in claim 9 , wherein a capacitance of the large capacitor is approximately ten times larger than a capacitance of the small capacitor.