1 files changed, 58 insertions, 0 deletions
diff --git a/fpga/usrp2/sdr_lib/rx_dcoffset.v b/fpga/usrp2/sdr_lib/rx_dcoffset.v
new file mode 100644
index 000000000..04d7795c0
--- /dev/null
+++ b/fpga/usrp2/sdr_lib/rx_dcoffset.v
@@ -0,0 +1,58 @@
+//
+// Copyright 2011 Ettus Research LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+//
+
+
+
+module rx_dcoffset 
+  #(parameter WIDTH=16,
+    parameter ADDR=8'd0,
+    parameter alpha_shift=20)
+   (input clk, input rst, 
+    input set_stb, input [7:0] set_addr, input [31:0] set_data,
+    input [WIDTH-1:0] in, output [WIDTH-1:0] out);
+   
+   wire 	      set_now = set_stb & (ADDR == set_addr);
+   
+   reg 		      fixed;  // uses fixed offset
+   wire [WIDTH-1:0]   fixed_dco;
+
+   localparam int_width = WIDTH + alpha_shift;
+   reg [int_width-1:0] integrator;
+   wire [WIDTH-1:0]    quantized;
+
+   always @(posedge clk)
+     if(rst)
+       begin
+	  fixed <= 0;
+	  integrator <= {int_width{1'b0}};
+       end
+     else if(set_now)
+       begin
+	  fixed <= set_data[31];
+	  if(set_data[30])
+	    integrator <= {set_data[29:0],{(int_width-30){1'b0}}};
+       end
+     else if(~fixed)
+       integrator <= integrator +  {{(alpha_shift){out[WIDTH-1]}},out};
+
+   round_sd #(.WIDTH_IN(int_width),.WIDTH_OUT(WIDTH)) round_sd
+     (.clk(clk), .reset(rst), .in(integrator), .strobe_in(1'b1), .out(quantized), .strobe_out());
+   
+   add2_and_clip_reg #(.WIDTH(WIDTH)) add2_and_clip_reg
+     (.clk(clk), .rst(rst), .in1(in), .in2(-quantized), .strobe_in(1'b1), .sum(out), .strobe_out());
+
+endmodule // rx_dcoffset