Mixer and method for generating an output signal from an input signal

Abstract

A mixer for generating an analog output signal X OUT from an analog input signal X IN using a mixing signal having a mixing frequency f MIX , the mixer comprising: a scaler being configured to sample the analog input signal X IN at a plurality of discrete points in time k with a sampling frequency f S to obtain a sampled analog input signal X IN [k] having a continuous signal value, and to generate the analog output signal X OUT having a continuous signal value by scaling the sampled analog input signal X IN [k] on the basis of a plurality of scaling coefficients A[k], wherein the scaling coefficients A[k] are a time-discrete representation of the mixing signal.

What is claimed is: 
     
         1 . A mixer for generating an analog output signal X OUT  from an analog input signal X IN  using a mixing signal having a mixing frequency f MIX , the mixer comprising:
 a scaler being configured to sample the analog input signal X IN  at a plurality of discrete points in time k with a sampling frequency f S  to obtain a sampled analog input signal X IN [k] having a continuous signal value, and to generate the analog output signal X OUT  having a continuous signal value by scaling the sampled analog input signal X IN [k] on the basis of a plurality of scaling coefficients A[k], wherein the scaling coefficients A[k] are a time-discrete representation of the mixing signal.   
     
     
         2 . The mixer of  claim 1 , wherein the sampling frequency f S  is equal to or larger than twice the mixing frequency f MIX  of the mixing signal. 
     
     
         3 . The mixer of  claim 1 , wherein the mixing signal is a sinusoidal mixing signal. 
     
     
         4 . The mixer of  claim 1 , wherein a ratio of the mixing frequency f MIX  to the sampling frequency f S  is given by AB with A and B being integers. 
     
     
         5 . The mixer of  claim 1 , wherein the scaler is configured to derive the sampling frequency f S  from a local oscillator frequency f LO  of a local oscillator signal provided by a local oscillator, wherein the sampling frequency f S  is an integer multiple of the local oscillator frequency f LO . 
     
     
         6 . The mixer of  claim 1 , wherein the analog input signal X IN  is an analog voltage signal V IN  or an analog current signal I IN  and wherein the analog output signal X OUT  is an analog voltage signal V OUT  or an analog current signal I OUT . 
     
     
         7 . The mixer of  claim 1 , wherein the mixer comprises an input terminal and an output terminal connected to the scaler and wherein the scaler comprises a plurality of unit cells connected in parallel to the input terminal, wherein each unit cell comprises a unit cell capacitor, wherein the unit cell capacitor of the i-th unit cell has a capacitance C ui  and wherein a sum of the capacitances of the unit cells defines a total capacitance C s , and wherein each unit cell comprises a charge transfer switch for connecting the unit cell capacitor of each unit cell to the output terminal, wherein the scaler is configured to control the charge transfer switch of each unit cell for scaling the sampled analog input signal X IN [k] on the basis of the plurality of scaling coefficients A[k]. 
     
     
         8 . The mixer of  claim 7 , wherein the plurality of unit cells comprises N unit cells and wherein the unit cell capacitors have the same capacitance C ui =C u  with C u  being a constant capacitance and the total capacitance C s  is given by C s =NC u , wherein N is an integer. 
     
     
         9 . The mixer of  claim 7 , wherein the plurality of unit cells comprises b unit cells, wherein the unit cell capacitor of the i-th unit cell has a capacitance C ui =2 i−1 C u  with C u  being a constant capacitance and the total capacitance C s  is given by C s =(2 b −1)C u , wherein b is an integer. 
     
     
         10 . The mixer of  claim 7 , wherein the plurality of unit cells comprises (b+K) unit cells, wherein the unit cell capacitor of the i-th unit cell of the b unit cells of the plurality of unit cells has a capacitance C ui =2 i−1 C u  with C u  being a constant capacitance, and wherein the unit cell capacitors of the K remaining unit cells of the plurality of unit cells have the same capacitance C ui =2 b C u  and the total capacitance C s  is given by C s =(2 b K+2 b −1)C u , wherein b and K are each integers. 
     
     
         11 . The mixer of  claim 7 , wherein the input terminal comprises a positive input terminal and a negative input terminal and wherein the output terminal comprises a positive output terminal and a negative output terminal and wherein each unit cell of the plurality of unit cells comprises a plurality of inversion switches, wherein the scaler is configured to control the plurality of inversion switches such that each side of the unit cell capacitor of a unit cell of the plurality of unit cells can be connected to the positive output terminal and/or the negative output terminal in order to operate the mixer differentially. 
     
     
         12 . The mixer of  claim 7 , wherein the scaler comprises a memory, the memory being configured to store a plurality of control codes, wherein each control code determines a fraction α[k] of the total capacitance C s  that is connected to the output terminal of the mixer. 
     
     
         13 . The mixer of  claim 7 , wherein the scaler comprises 2 M  blocks of unit cells, wherein M is an integer and wherein each block of unit cells is configured to sample the sampled analog input signal X IN [k] with a different phase, and wherein each block uses a different set of scaling factors A[k]. 
     
     
         14 . A method for generating an analog output signal X OUT  from an analog input signal X IN  using a mixing signal having a mixing frequency f MIX , the method comprising the steps of:
 sampling the analog input signal X IN  at a plurality of discrete points in time k with a sampling frequency f S  to obtain a sampled analog input signal X IN [k] having a continuous signal value; and   generating the analog output signal X OUT  having a continuous signal value by scaling the sampled analog input signal X IN [k] on the basis of a plurality of scaling coefficients A[k], wherein the scaling coefficients A[k] are a time-discrete representation of the periodic mixing signal.   
     
     
         15 . A non-transitory computer readable medium comprising a computer program with a program code for performing the method of  claim 14  when executed on a computer. 
     
     
         16 . The mixer of  claim 5 , wherein the sampling frequency f S  is equal to four times the local oscillator frequency f LO .